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freebsd-dev/sys/kern/subr_turnstile.c

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Major update to the way synchronization is done in the kernel. Highlights include: * Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The alpha port is still in transition and currently uses both.) * Per-CPU idle processes. * Interrupts are run in their own separate kernel threads and can be preempted (i386 only). Partially contributed by: BSDi (BSD/OS) Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
/*-
* Copyright (c) 1998 Berkeley Software Design, Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Berkeley Software Design Inc's name may not be used to endorse or
* promote products derived from this software without specific prior
* written permission.
*
* THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN INC ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN INC BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* from BSDI $Id: mutex_witness.c,v 1.1.2.20 2000/04/27 03:10:27 cp Exp $
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
* and BSDI $Id: synch_machdep.c,v 2.3.2.39 2000/04/27 03:10:25 cp Exp $
Major update to the way synchronization is done in the kernel. Highlights include: * Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The alpha port is still in transition and currently uses both.) * Per-CPU idle processes. * Interrupts are run in their own separate kernel threads and can be preempted (i386 only). Partially contributed by: BSDi (BSD/OS) Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
*/
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Implementation of turnstiles used to hold queue of threads blocked on
* non-sleepable locks. Sleepable locks use condition variables to
* implement their queues. Turnstiles differ from a sleep queue in that
* turnstile queue's are assigned to a lock held by an owning thread. Thus,
* when one thread is enqueued onto a turnstile, it can lend its priority
* to the owning thread.
*
* We wish to avoid bloating locks with an embedded turnstile and we do not
* want to use back-pointers in the locks for the same reason. Thus, we
* use a similar approach to that of Solaris 7 as described in Solaris
* Internals by Jim Mauro and Richard McDougall. Turnstiles are looked up
* in a hash table based on the address of the lock. Each entry in the
* hash table is a linked-lists of turnstiles and is called a turnstile
* chain. Each chain contains a spin mutex that protects all of the
* turnstiles in the chain.
*
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
* Each time a thread is created, a turnstile is allocated from a UMA zone
* and attached to that thread. When a thread blocks on a lock, if it is the
* first thread to block, it lends its turnstile to the lock. If the lock
* already has a turnstile, then it gives its turnstile to the lock's
* turnstile's free list. When a thread is woken up, it takes a turnstile from
* the free list if there are any other waiters. If it is the only thread
* blocked on the lock, then it reclaims the turnstile associated with the lock
* and removes it from the hash table.
Major update to the way synchronization is done in the kernel. Highlights include: * Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The alpha port is still in transition and currently uses both.) * Per-CPU idle processes. * Interrupts are run in their own separate kernel threads and can be preempted (i386 only). Partially contributed by: BSDi (BSD/OS) Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
*/
Use __FBSDID().
2003-06-11 00:56:59 +00:00
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
#include "opt_ddb.h"
#include "opt_turnstile_profiling.h"
- Include opt_sched.h for SCHED_STATS.
2007-06-12 23:27:31 +00:00
#include "opt_sched.h"
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
Major update to the way synchronization is done in the kernel. Highlights include: * Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The alpha port is still in transition and currently uses both.) * Per-CPU idle processes. * Interrupts are run in their own separate kernel threads and can be preempted (i386 only). Partially contributed by: BSDi (BSD/OS) Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
#include <sys/param.h>
Mutex profiling code, conditional on the MUTEX_PROFILING option. Adds the following sysctl variables: debug.mutex.prof.enable enable / disable profiling debug.mutex.prof.acquisitions number of mutex acquisitions recorded debug.mutex.prof.records number of acquisition points recorded debug.mutex.prof.maxrecords max number of acquisition points debug.mutex.prof.rejected number of rejections (due to full table) debug.mutex.prof.hashsize hash size debug.mutex.prof.collisions number of hash collisions debug.mutex.prof.stats profiling statistics The code records four numbers for each acquisition point (identified by source file name and line number): longest time held, total time held, number of non-recursive acquisitions, average time held. The measurements are in clock cycles (as returned by get_cyclecount(9)); this may cause measurements on some SMP systems to be unreliable. This can probably be worked around by replacing get_cyclecount(9) by some incarnation of nanotime(9). This work was derived from initial patches by eivind.
2002-04-02 00:01:49 +00:00
#include <sys/systm.h>
Fix !DDB build after r234190.
2012-04-14 11:21:24 +00:00
#include <sys/kdb.h>
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
#include <sys/kernel.h>
Mutex profiling code, conditional on the MUTEX_PROFILING option. Adds the following sysctl variables: debug.mutex.prof.enable enable / disable profiling debug.mutex.prof.acquisitions number of mutex acquisitions recorded debug.mutex.prof.records number of acquisition points recorded debug.mutex.prof.maxrecords max number of acquisition points debug.mutex.prof.rejected number of rejections (due to full table) debug.mutex.prof.hashsize hash size debug.mutex.prof.collisions number of hash collisions debug.mutex.prof.stats profiling statistics The code records four numbers for each acquisition point (identified by source file name and line number): longest time held, total time held, number of non-recursive acquisitions, average time held. The measurements are in clock cycles (as returned by get_cyclecount(9)); this may cause measurements on some SMP systems to be unreliable. This can probably be worked around by replacing get_cyclecount(9) by some incarnation of nanotime(9). This work was derived from initial patches by eivind.
2002-04-02 00:01:49 +00:00
#include <sys/ktr.h>
Rework the witness code to work with sx locks as well as mutexes. - Introduce lock classes and lock objects. Each lock class specifies a name and set of flags (or properties) shared by all locks of a given type. Currently there are three lock classes: spin mutexes, sleep mutexes, and sx locks. A lock object specifies properties of an additional lock along with a lock name and all of the extra stuff needed to make witness work with a given lock. This abstract lock stuff is defined in sys/lock.h. The lockmgr constants, types, and prototypes have been moved to sys/lockmgr.h. For temporary backwards compatability, sys/lock.h includes sys/lockmgr.h. - Replace proc->p_spinlocks with a per-CPU list, PCPU(spinlocks), of spin locks held. By making this per-cpu, we do not have to jump through magic hoops to deal with sched_lock changing ownership during context switches. - Replace proc->p_heldmtx, formerly a list of held sleep mutexes, with proc->p_sleeplocks, which is a list of held sleep locks including sleep mutexes and sx locks. - Add helper macros for logging lock events via the KTR_LOCK KTR logging level so that the log messages are consistent. - Add some new flags that can be passed to mtx_init(): - MTX_NOWITNESS - specifies that this lock should be ignored by witness. This is used for the mutex that blocks a sx lock for example. - MTX_QUIET - this is not new, but you can pass this to mtx_init() now and no events will be logged for this lock, so that one doesn't have to change all the individual mtx_lock/unlock() operations. - All lock objects maintain an initialized flag. Use this flag to export a mtx_initialized() macro that can be safely called from drivers. Also, we on longer walk the all_mtx list if MUTEX_DEBUG is defined as witness performs the corresponding checks using the initialized flag. - The lock order reversal messages have been improved to output slightly more accurate file and line numbers.
2001-03-28 09:03:24 +00:00
#include <sys/lock.h>
#include <sys/mutex.h>
Major update to the way synchronization is done in the kernel. Highlights include: * Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The alpha port is still in transition and currently uses both.) * Per-CPU idle processes. * Interrupts are run in their own separate kernel threads and can be preempted (i386 only). Partially contributed by: BSDi (BSD/OS) Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
#include <sys/proc.h>
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
#include <sys/queue.h>
- Create a new scheduler api that is defined in sys/sched.h - Begin moving scheduler specific functionality into sched_4bsd.c - Replace direct manipulation of scheduler data with hooks provided by the new api. - Remove KSE specific state modifications and single runq assumptions from kern_switch.c Reviewed by: -arch
2002-10-12 05:32:24 +00:00
#include <sys/sched.h>
Implement the DTrace sched provider. This implementation aims to be compatible with the sched provider implemented by Solaris and its open- source derivatives. Full documentation of the sched provider can be found on Oracle's DTrace wiki pages. Note that for compatibility with scripts originally written for Solaris, serveral probes are defined that will never fire. These probes are defined to fire when Solaris-specific features perform certain actions. As these features are not present in FreeBSD, the probes can never fire. Also, I have added a two probes that are not defined in Solaris, lend-pri and load-change. These probes have been added to make it possible to collect schedgraph data with DTrace. Finally, a few probes are defined in Solaris to take a cpuinfo_t * argument. As it was not immediately clear to me how to translate that to FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *. Sponsored by: Sandvine Incorporated MFC after: 2 weeks
2012-05-15 01:30:25 +00:00
#include <sys/sdt.h>
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#include <sys/sysctl.h>
#include <sys/turnstile.h>
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
#include <vm/uma.h>
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
#ifdef DDB
#include <ddb/ddb.h>
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
#include <sys/lockmgr.h>
#include <sys/sx.h>
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
#endif
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Constants for the hash table of turnstile chains. TC_SHIFT is a magic
* number chosen because the sleep queue's use the same value for the
* shift. Basically, we ignore the lower 8 bits of the address.
* TC_TABLESIZE must be a power of two for TC_MASK to work properly.
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
#define TC_TABLESIZE 128 /* Must be power of 2. */
#define TC_MASK (TC_TABLESIZE - 1)
#define TC_SHIFT 8
#define TC_HASH(lock) (((uintptr_t)(lock) >> TC_SHIFT) & TC_MASK)
#define TC_LOOKUP(lock) &turnstile_chains[TC_HASH(lock)]
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* There are three different lists of turnstiles as follows. The list
* connected by ts_link entries is a per-thread list of all the turnstiles
* attached to locks that we own. This is used to fixup our priority when
* a lock is released. The other two lists use the ts_hash entries. The
Clarify and tweak some comments.
2004-02-27 16:14:27 +00:00
* first of these two is the turnstile chain list that a turnstile is on
* when it is attached to a lock. The second list to use ts_hash is the
* free list hung off of a turnstile that is attached to a lock.
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
*
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
* Each turnstile contains three lists of threads. The two ts_blocked lists
* are linked list of threads blocked on the turnstile's lock. One list is
* for exclusive waiters, and the other is for shared waiters. The
Fixup a comment.
2004-03-12 19:05:46 +00:00
* ts_pending list is a linked list of threads previously awakened by
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* turnstile_signal() or turnstile_wait() that are waiting to be put on
* the run queue.
*
* Locking key:
* c - turnstile chain lock
* q - td_contested lock
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile {
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
struct mtx ts_lock; /* Spin lock for self. */
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
struct threadqueue ts_blocked[2]; /* (c + q) Blocked threads. */
struct threadqueue ts_pending; /* (c) Pending threads. */
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
LIST_ENTRY(turnstile) ts_hash; /* (c) Chain and free list. */
LIST_ENTRY(turnstile) ts_link; /* (q) Contested locks. */
LIST_HEAD(, turnstile) ts_free; /* (c) Free turnstiles. */
struct lock_object *ts_lockobj; /* (c) Lock we reference. */
- Close a race where a thread on another CPU could release a contested lock and empty its turnstile while the blocking threads still pointed to the turnstile. If the thread on the first CPU blocked on a lock owned by one of the threads blocked on the turnstile just woken up, then the first CPU could try to manipulate a bogus thread queue in the turnstile during priority propagation. - Update locking notes for ts_owner and always clear ts_owner, not just under INVARIANTS. Tested by: sam (1)
2003-11-12 23:48:42 +00:00
struct thread *ts_owner; /* (c + q) Who owns the lock. */
Rework the witness code to work with sx locks as well as mutexes. - Introduce lock classes and lock objects. Each lock class specifies a name and set of flags (or properties) shared by all locks of a given type. Currently there are three lock classes: spin mutexes, sleep mutexes, and sx locks. A lock object specifies properties of an additional lock along with a lock name and all of the extra stuff needed to make witness work with a given lock. This abstract lock stuff is defined in sys/lock.h. The lockmgr constants, types, and prototypes have been moved to sys/lockmgr.h. For temporary backwards compatability, sys/lock.h includes sys/lockmgr.h. - Replace proc->p_spinlocks with a per-CPU list, PCPU(spinlocks), of spin locks held. By making this per-cpu, we do not have to jump through magic hoops to deal with sched_lock changing ownership during context switches. - Replace proc->p_heldmtx, formerly a list of held sleep mutexes, with proc->p_sleeplocks, which is a list of held sleep locks including sleep mutexes and sx locks. - Add helper macros for logging lock events via the KTR_LOCK KTR logging level so that the log messages are consistent. - Add some new flags that can be passed to mtx_init(): - MTX_NOWITNESS - specifies that this lock should be ignored by witness. This is used for the mutex that blocks a sx lock for example. - MTX_QUIET - this is not new, but you can pass this to mtx_init() now and no events will be logged for this lock, so that one doesn't have to change all the individual mtx_lock/unlock() operations. - All lock objects maintain an initialized flag. Use this flag to export a mtx_initialized() macro that can be safely called from drivers. Also, we on longer walk the all_mtx list if MUTEX_DEBUG is defined as witness performs the corresponding checks using the initialized flag. - The lock order reversal messages have been improved to output slightly more accurate file and line numbers.
2001-03-28 09:03:24 +00:00
};
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile_chain {
LIST_HEAD(, turnstile) tc_turnstiles; /* List of turnstiles. */
struct mtx tc_lock; /* Spin lock for this chain. */
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#ifdef TURNSTILE_PROFILING
u_int tc_depth; /* Length of tc_queues. */
u_int tc_max_depth; /* Max length of tc_queues. */
#endif
Rework the witness code to work with sx locks as well as mutexes. - Introduce lock classes and lock objects. Each lock class specifies a name and set of flags (or properties) shared by all locks of a given type. Currently there are three lock classes: spin mutexes, sleep mutexes, and sx locks. A lock object specifies properties of an additional lock along with a lock name and all of the extra stuff needed to make witness work with a given lock. This abstract lock stuff is defined in sys/lock.h. The lockmgr constants, types, and prototypes have been moved to sys/lockmgr.h. For temporary backwards compatability, sys/lock.h includes sys/lockmgr.h. - Replace proc->p_spinlocks with a per-CPU list, PCPU(spinlocks), of spin locks held. By making this per-cpu, we do not have to jump through magic hoops to deal with sched_lock changing ownership during context switches. - Replace proc->p_heldmtx, formerly a list of held sleep mutexes, with proc->p_sleeplocks, which is a list of held sleep locks including sleep mutexes and sx locks. - Add helper macros for logging lock events via the KTR_LOCK KTR logging level so that the log messages are consistent. - Add some new flags that can be passed to mtx_init(): - MTX_NOWITNESS - specifies that this lock should be ignored by witness. This is used for the mutex that blocks a sx lock for example. - MTX_QUIET - this is not new, but you can pass this to mtx_init() now and no events will be logged for this lock, so that one doesn't have to change all the individual mtx_lock/unlock() operations. - All lock objects maintain an initialized flag. Use this flag to export a mtx_initialized() macro that can be safely called from drivers. Also, we on longer walk the all_mtx list if MUTEX_DEBUG is defined as witness performs the corresponding checks using the initialized flag. - The lock order reversal messages have been improved to output slightly more accurate file and line numbers.
2001-03-28 09:03:24 +00:00
};
- Place back STR string declarations for lock/unlock strings used for KTR_LOCK tracing in order to avoid duplication. - Insert some tracepoints back into the mutex acq/rel code, thus ensuring that we can trace all lock acq/rel's again. - All CURPROC != NULL checks are MPASS()es (under MUTEX_DEBUG) because they signify a serious mutex corruption. - Change up some KASSERT()s to MPASS()es, and vice-versa, depending on the type of problem we're debugging (INVARIANTS is used here to check that the API is being used properly whereas MUTEX_DEBUG is used to ensure that something general isn't happening that will have bad impact on mutex locks). Reminded by: jhb, jake, asmodai
2001-02-11 02:54:16 +00:00
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#ifdef TURNSTILE_PROFILING
u_int turnstile_max_depth;
Mark all SYSCTL_NODEs static that have no corresponding SYSCTL_DECLs. The SYSCTL_NODE macro defines a list that stores all child-elements of that node. If there's no SYSCTL_DECL macro anywhere else, there's no reason why it shouldn't be static.
2011-11-07 15:43:11 +00:00
static SYSCTL_NODE(_debug, OID_AUTO, turnstile, CTLFLAG_RD, 0,
"turnstile profiling");
static SYSCTL_NODE(_debug_turnstile, OID_AUTO, chains, CTLFLAG_RD, 0,
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
"turnstile chain stats");
SYSCTL_UINT(_debug_turnstile, OID_AUTO, max_depth, CTLFLAG_RD,
Fix a typo. Approved by: gnn (mentor) MFC after: 2 days
2012-04-14 23:59:58 +00:00
&turnstile_max_depth, 0, "maximum depth achieved of a single chain");
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#endif
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
static struct mtx td_contested_lock;
static struct turnstile_chain turnstile_chains[TC_TABLESIZE];
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
static uma_zone_t turnstile_zone;
- Move the MI mutexes sched_lock and Giant from being declared in the various machdep.c's to being declared in kern_mutex.c. - Add a new function mutex_init() used to perform early initialization needed for mutexes such as setting up thread0's contested lock list and initializing MI mutexes. Change the various MD startup routines to call this function instead of duplicating all the code themselves. Tested on: alpha, i386
2002-04-02 22:19:16 +00:00
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
/*
* Prototypes for non-exported routines.
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
static void init_turnstile0(void *dummy);
Oops, this didn't make it into my submit before I committed: Defer creation of the sysctl tree for the turnstile profiling stats until a SI_SUB_LOCK sysinit. Doing it in init_turnstiles() is too early as it is called before mi_startup().
2004-06-29 03:48:49 +00:00
#ifdef TURNSTILE_PROFILING
static void init_turnstile_profiling(void *arg);
#endif
ddb(4): Add sleepchains to "show allchains" Reported by: markj Reviewed by: markj Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D8320
2016-10-22 18:02:20 +00:00
#ifdef DDB
static void print_sleepchain(struct thread *td, const char *prefix);
#endif
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
static void propagate_priority(struct thread *td);
static int turnstile_adjust_thread(struct turnstile *ts,
struct thread *td);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
static struct thread *turnstile_first_waiter(struct turnstile *ts);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
static void turnstile_setowner(struct turnstile *ts, struct thread *owner);
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
#ifdef INVARIANTS
static void turnstile_dtor(void *mem, int size, void *arg);
#endif
static int turnstile_init(void *mem, int size, int flags);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
static void turnstile_fini(void *mem, int size);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Implement the DTrace sched provider. This implementation aims to be compatible with the sched provider implemented by Solaris and its open- source derivatives. Full documentation of the sched provider can be found on Oracle's DTrace wiki pages. Note that for compatibility with scripts originally written for Solaris, serveral probes are defined that will never fire. These probes are defined to fire when Solaris-specific features perform certain actions. As these features are not present in FreeBSD, the probes can never fire. Also, I have added a two probes that are not defined in Solaris, lend-pri and load-change. These probes have been added to make it possible to collect schedgraph data with DTrace. Finally, a few probes are defined in Solaris to take a cpuinfo_t * argument. As it was not immediately clear to me how to translate that to FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *. Sponsored by: Sandvine Incorporated MFC after: 2 weeks
2012-05-15 01:30:25 +00:00
SDT_PROVIDER_DECLARE(sched);
dtrace sdt: remove the ugly sname parameter of SDT_PROBE_DEFINE In its stead use the Solaris / illumos approach of emulating '-' (dash) in probe names with '__' (two consecutive underscores). Reviewed by: markj MFC after: 3 weeks
2013-11-26 08:46:27 +00:00
SDT_PROBE_DEFINE(sched, , , sleep);
SDT_PROBE_DEFINE2(sched, , , wakeup, "struct thread *",
Implement the DTrace sched provider. This implementation aims to be compatible with the sched provider implemented by Solaris and its open- source derivatives. Full documentation of the sched provider can be found on Oracle's DTrace wiki pages. Note that for compatibility with scripts originally written for Solaris, serveral probes are defined that will never fire. These probes are defined to fire when Solaris-specific features perform certain actions. As these features are not present in FreeBSD, the probes can never fire. Also, I have added a two probes that are not defined in Solaris, lend-pri and load-change. These probes have been added to make it possible to collect schedgraph data with DTrace. Finally, a few probes are defined in Solaris to take a cpuinfo_t * argument. As it was not immediately clear to me how to translate that to FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *. Sponsored by: Sandvine Incorporated MFC after: 2 weeks
2012-05-15 01:30:25 +00:00
"struct proc *");
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Walks the chain of turnstiles and their owners to propagate the priority
* of the thread being blocked to all the threads holding locks that have to
* release their locks before this thread can run again.
*/
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
static void
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
propagate_priority(struct thread *td)
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile *ts;
int pri;
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
THREAD_LOCK_ASSERT(td, MA_OWNED);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
pri = td->td_priority;
ts = td->td_blocked;
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts. Sponsored by: Nokia
2008-02-07 06:55:38 +00:00
THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
/*
* Grab a recursive lock on this turnstile chain so it stays locked
* for the whole operation. The caller expects us to return with
* the original lock held. We only ever lock down the chain so
* the lock order is constant.
*/
mtx_lock_spin(&ts->ts_lock);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
for (;;) {
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
td = ts->ts_owner;
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
if (td == NULL) {
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
/*
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
* This might be a read lock with no owner. There's
* not much we can do, so just bail.
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
*/
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_unlock_spin(&ts->ts_lock);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
return;
}
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_lock_flags(td, MTX_DUPOK);
mtx_unlock_spin(&ts->ts_lock);
Part 1 of KSE-III The ability to schedule multiple threads per process (one one cpu) by making ALL system calls optionally asynchronous. to come: ia64 and power-pc patches, patches for gdb, test program (in tools) Reviewed by: Almost everyone who counts (at various times, peter, jhb, matt, alfred, mini, bernd, and a cast of thousands) NOTE: this is still Beta code, and contains lots of debugging stuff. expect slight instability in signals..
2002-06-29 17:26:22 +00:00
MPASS(td->td_proc != NULL);
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
MPASS(td->td_proc->p_magic == P_MAGIC);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
Always explicitly panic in propogate_priority() if we try to propogate a lock's priority to a sleeping thread. When we panic, dump a stack trace of the thread that is asleep if DDB is compiled into the kernel just before calling panic(). This is much more informative and useful for debugging than the current behavior of getting a page fault and not having an easy way of determining which thread caused the original problem. MFC after: 1 week
2006-03-29 23:24:55 +00:00
* If the thread is asleep, then we are probably about
Update the comment: we do show the backtrace of misbehaving thread.
2013-02-17 21:37:32 +00:00
* to deadlock. To make debugging this easier, show
* backtrace of misbehaving thread and panic to not
* leave the kernel deadlocked.
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
*/
Always explicitly panic in propogate_priority() if we try to propogate a lock's priority to a sleeping thread. When we panic, dump a stack trace of the thread that is asleep if DDB is compiled into the kernel just before calling panic(). This is much more informative and useful for debugging than the current behavior of getting a page fault and not having an easy way of determining which thread caused the original problem. MFC after: 1 week
2006-03-29 23:24:55 +00:00
if (TD_IS_SLEEPING(td)) {
printf(
"Sleeping thread (tid %d, pid %d) owns a non-sleepable lock\n",
td->td_tid, td->td_proc->p_pid);
- Extend the KDB interface to add a per-debugger callback to print a backtrace for an arbitrary thread (rather than the calling thread). A kdb_backtrace_thread() wrapper function uses the configured debugger if possible, otherwise it falls back to using stack(9) if that is available. - Replace a direct call to db_trace_thread() in propagate_priority() with a call to kdb_backtrace_thread() instead. MFC after: 1 week
2012-04-12 17:43:59 +00:00
kdb_backtrace_thread(td);
Always explicitly panic in propogate_priority() if we try to propogate a lock's priority to a sleeping thread. When we panic, dump a stack trace of the thread that is asleep if DDB is compiled into the kernel just before calling panic(). This is much more informative and useful for debugging than the current behavior of getting a page fault and not having an easy way of determining which thread caused the original problem. MFC after: 1 week
2006-03-29 23:24:55 +00:00
panic("sleeping thread");
}
Fix up priority propagation: - Use a better test for determining when a process is running. - Convert some checks to assertions. - Remove unnecessary tests. - Save the priority before acquiring a mutex rather than in msleep(9).
2000-11-30 00:51:16 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* If this thread already has higher priority than the
* thread that is being blocked, we are finished.
*/
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
if (td->td_priority <= pri) {
thread_unlock(td);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
return;
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
}
Fix up priority propagation: - Use a better test for determining when a process is running. - Convert some checks to assertions. - Remove unnecessary tests. - Save the priority before acquiring a mutex rather than in msleep(9).
2000-11-30 00:51:16 +00:00
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
/*
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
* Bump this thread's priority.
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
*/
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
sched_lend_prio(td, pri);
/*
* If lock holder is actually running or on the run queue
* then we are done.
*/
if (TD_IS_RUNNING(td) || TD_ON_RUNQ(td)) {
MPASS(td->td_blocked == NULL);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_unlock(td);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
return;
}
Implement a unified run queue and adjust priority levels accordingly. - All processes go into the same array of queues, with different scheduling classes using different portions of the array. This allows user processes to have their priorities propogated up into interrupt thread range if need be. - I chose 64 run queues as an arbitrary number that is greater than 32. We used to have 4 separate arrays of 32 queues each, so this may not be optimal. The new run queue code was written with this in mind; changing the number of run queues only requires changing constants in runq.h and adjusting the priority levels. - The new run queue code takes the run queue as a parameter. This is intended to be used to create per-cpu run queues. Implement wrappers for compatibility with the old interface which pass in the global run queue structure. - Group the priority level, user priority, native priority (before propogation) and the scheduling class into a struct priority. - Change any hard coded priority levels that I found to use symbolic constants (TTIPRI and TTOPRI). - Remove the curpriority global variable and use that of curproc. This was used to detect when a process' priority had lowered and it should yield. We now effectively yield on every interrupt. - Activate propogate_priority(). It should now have the desired effect without needing to also propogate the scheduling class. - Temporarily comment out the call to vm_page_zero_idle() in the idle loop. It interfered with propogate_priority() because the idle process needed to do a non-blocking acquire of Giant and then other processes would try to propogate their priority onto it. The idle process should not do anything except idle. vm_page_zero_idle() will return in the form of an idle priority kernel thread which is woken up at apprioriate times by the vm system. - Update struct kinfo_proc to the new priority interface. Deliberately change its size by adjusting the spare fields. It remained the same size, but the layout has changed, so userland processes that use it would parse the data incorrectly. The size constraint should really be changed to an arbitrary version number. Also add a debug.sizeof sysctl node for struct kinfo_proc.
2001-02-12 00:20:08 +00:00
- Add an extra check in priority_propagation() for UP systems to ensure we don't end up back at ourselves which would indicate deadlock. - Add the proc lock to the witness dup_list as we may hold more than one process lock at a time. - Don't assert a mutex is owned in _mtx_unlock_sleep() as that is too late. We do the checks in the macros instead.
2001-03-07 02:45:15 +00:00
#ifndef SMP
/*
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
* For UP, we check to see if td is curthread (this shouldn't
- Add an extra check in priority_propagation() for UP systems to ensure we don't end up back at ourselves which would indicate deadlock. - Add the proc lock to the witness dup_list as we may hold more than one process lock at a time. - Don't assert a mutex is owned in _mtx_unlock_sleep() as that is too late. We do the checks in the macros instead.
2001-03-07 02:45:15 +00:00
* ever happen however as it would mean we are in a deadlock.)
*/
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
KASSERT(td != curthread, ("Deadlock detected"));
- Add an extra check in priority_propagation() for UP systems to ensure we don't end up back at ourselves which would indicate deadlock. - Add the proc lock to the witness dup_list as we may hold more than one process lock at a time. - Don't assert a mutex is owned in _mtx_unlock_sleep() as that is too late. We do the checks in the macros instead.
2001-03-07 02:45:15 +00:00
#endif
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* If we aren't blocked on a lock, we should be.
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
*/
Rename the mutex thread and process states to use a more generic 'LOCK' name instead. (e.g., SLOCK instead of SMTX, TD_ON_LOCK() instead of TD_ON_MUTEX()) Eventually a turnstile abstraction will be added that will be shared with mutexes and other types of locks. SLOCK/TDI_LOCK will be used internally by the turnstile code and will not be specific to mutexes. Making the change now ensures that turnstiles can be dropped in at a later date without affecting the ABI of userland applications.
2002-10-02 20:31:47 +00:00
KASSERT(TD_ON_LOCK(td), (
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
"thread %d(%s):%d holds %s but isn't blocked on a lock\n",
generally we are interested in what thread did something as opposed to what process. Since threads by default have teh name of the process unless over-written with more useful information, just print the thread name instead.
2007-11-14 06:21:24 +00:00
td->td_tid, td->td_name, td->td_state,
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
ts->ts_lockobj->lo_name));
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Pick up the lock that td is blocked on.
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
ts = td->td_blocked;
MPASS(ts != NULL);
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts. Sponsored by: Nokia
2008-02-07 06:55:38 +00:00
THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
/* Resort td on the list if needed. */
if (!turnstile_adjust_thread(ts, td)) {
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_unlock_spin(&ts->ts_lock);
- Close a race where a thread on another CPU could release a contested lock and empty its turnstile while the blocking threads still pointed to the turnstile. If the thread on the first CPU blocked on a lock owned by one of the threads blocked on the turnstile just woken up, then the first CPU could try to manipulate a bogus thread queue in the turnstile during priority propagation. - Update locking notes for ts_owner and always clear ts_owner, not just under INVARIANTS. Tested by: sam (1)
2003-11-12 23:48:42 +00:00
return;
}
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
/* The thread lock is released as ts lock above. */
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
}
}
- Close a race where a thread on another CPU could release a contested lock and empty its turnstile while the blocking threads still pointed to the turnstile. If the thread on the first CPU blocked on a lock owned by one of the threads blocked on the turnstile just woken up, then the first CPU could try to manipulate a bogus thread queue in the turnstile during priority propagation. - Update locking notes for ts_owner and always clear ts_owner, not just under INVARIANTS. Tested by: sam (1)
2003-11-12 23:48:42 +00:00
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
/*
* Adjust the thread's position on a turnstile after its priority has been
* changed.
*/
static int
turnstile_adjust_thread(struct turnstile *ts, struct thread *td)
{
struct thread *td1, *td2;
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
int queue;
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
THREAD_LOCK_ASSERT(td, MA_OWNED);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
MPASS(TD_ON_LOCK(td));
/*
* This thread may not be blocked on this turnstile anymore
* but instead might already be woken up on another CPU
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
* that is waiting on the thread lock in turnstile_unpend() to
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
* finish waking this thread up. We can detect this case
* by checking to see if this thread has been given a
* turnstile by either turnstile_signal() or
* turnstile_broadcast(). In this case, treat the thread as
* if it was already running.
*/
if (td->td_turnstile != NULL)
return (0);
/*
* Check if the thread needs to be moved on the blocked chain.
* It needs to be moved if either its priority is lower than
* the previous thread or higher than the next thread.
*/
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts. Sponsored by: Nokia
2008-02-07 06:55:38 +00:00
THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
td1 = TAILQ_PREV(td, threadqueue, td_lockq);
td2 = TAILQ_NEXT(td, td_lockq);
if ((td1 != NULL && td->td_priority < td1->td_priority) ||
(td2 != NULL && td->td_priority > td2->td_priority)) {
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
/*
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
* Remove thread from blocked chain and determine where
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
* it should be moved to.
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
*/
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
queue = td->td_tsqueue;
MPASS(queue == TS_EXCLUSIVE_QUEUE || queue == TS_SHARED_QUEUE);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
mtx_lock_spin(&td_contested_lock);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq);
TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq) {
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
MPASS(td1->td_proc->p_magic == P_MAGIC);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
if (td1->td_priority > td->td_priority)
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
break;
}
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
if (td1 == NULL)
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
else
TAILQ_INSERT_BEFORE(td1, td, td_lockq);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
mtx_unlock_spin(&td_contested_lock);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
if (td1 == NULL)
CTR3(KTR_LOCK,
"turnstile_adjust_thread: td %d put at tail on [%p] %s",
td->td_tid, ts->ts_lockobj, ts->ts_lockobj->lo_name);
else
CTR4(KTR_LOCK,
"turnstile_adjust_thread: td %d moved before %d on [%p] %s",
td->td_tid, td1->td_tid, ts->ts_lockobj,
ts->ts_lockobj->lo_name);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
}
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
return (1);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
}
Mutex profiling code, conditional on the MUTEX_PROFILING option. Adds the following sysctl variables: debug.mutex.prof.enable enable / disable profiling debug.mutex.prof.acquisitions number of mutex acquisitions recorded debug.mutex.prof.records number of acquisition points recorded debug.mutex.prof.maxrecords max number of acquisition points debug.mutex.prof.rejected number of rejections (due to full table) debug.mutex.prof.hashsize hash size debug.mutex.prof.collisions number of hash collisions debug.mutex.prof.stats profiling statistics The code records four numbers for each acquisition point (identified by source file name and line number): longest time held, total time held, number of non-recursive acquisitions, average time held. The measurements are in clock cycles (as returned by get_cyclecount(9)); this may cause measurements on some SMP systems to be unreliable. This can probably be worked around by replacing get_cyclecount(9) by some incarnation of nanotime(9). This work was derived from initial patches by eivind.
2002-04-02 00:01:49 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Early initialization of turnstiles. This is not done via a SYSINIT()
* since this needs to be initialized very early when mutexes are first
* initialized.
Mutex profiling code, conditional on the MUTEX_PROFILING option. Adds the following sysctl variables: debug.mutex.prof.enable enable / disable profiling debug.mutex.prof.acquisitions number of mutex acquisitions recorded debug.mutex.prof.records number of acquisition points recorded debug.mutex.prof.maxrecords max number of acquisition points debug.mutex.prof.rejected number of rejections (due to full table) debug.mutex.prof.hashsize hash size debug.mutex.prof.collisions number of hash collisions debug.mutex.prof.stats profiling statistics The code records four numbers for each acquisition point (identified by source file name and line number): longest time held, total time held, number of non-recursive acquisitions, average time held. The measurements are in clock cycles (as returned by get_cyclecount(9)); this may cause measurements on some SMP systems to be unreliable. This can probably be worked around by replacing get_cyclecount(9) by some incarnation of nanotime(9). This work was derived from initial patches by eivind.
2002-04-02 00:01:49 +00:00
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
void
init_turnstiles(void)
Instead of get_cyclecount(9), use nanotime(9) to record acquisition and release times. Measurements are made and stored in nanoseconds but presented in microseconds, which should be sufficient for the locks for which we actually want this (those that are held long and / or often). Also, rename some variables and structure members to unit-agnostic names.
2002-04-02 14:42:01 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
int i;
Instead of get_cyclecount(9), use nanotime(9) to record acquisition and release times. Measurements are made and stored in nanoseconds but presented in microseconds, which should be sufficient for the locks for which we actually want this (those that are held long and / or often). Also, rename some variables and structure members to unit-agnostic names.
2002-04-02 14:42:01 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
for (i = 0; i < TC_TABLESIZE; i++) {
LIST_INIT(&turnstile_chains[i].tc_turnstiles);
mtx_init(&turnstile_chains[i].tc_lock, "turnstile chain",
NULL, MTX_SPIN);
Oops, this didn't make it into my submit before I committed: Defer creation of the sysctl tree for the turnstile profiling stats until a SI_SUB_LOCK sysinit. Doing it in init_turnstiles() is too early as it is called before mi_startup().
2004-06-29 03:48:49 +00:00
}
mtx_init(&td_contested_lock, "td_contested", NULL, MTX_SPIN);
Initialize thread0.td_contested in init_turnstiles() rather than mutex_init() as it is used by the turnstile code and is not mutex-specific.
2006-01-17 16:47:42 +00:00
LIST_INIT(&thread0.td_contested);
Oops, this didn't make it into my submit before I committed: Defer creation of the sysctl tree for the turnstile profiling stats until a SI_SUB_LOCK sysinit. Doing it in init_turnstiles() is too early as it is called before mi_startup().
2004-06-29 03:48:49 +00:00
thread0.td_turnstile = NULL;
}
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#ifdef TURNSTILE_PROFILING
Oops, this didn't make it into my submit before I committed: Defer creation of the sysctl tree for the turnstile profiling stats until a SI_SUB_LOCK sysinit. Doing it in init_turnstiles() is too early as it is called before mi_startup().
2004-06-29 03:48:49 +00:00
static void
init_turnstile_profiling(void *arg)
{
struct sysctl_oid *chain_oid;
char chain_name[10];
int i;
for (i = 0; i < TC_TABLESIZE; i++) {
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
snprintf(chain_name, sizeof(chain_name), "%d", i);
chain_oid = SYSCTL_ADD_NODE(NULL,
SYSCTL_STATIC_CHILDREN(_debug_turnstile_chains), OID_AUTO,
chain_name, CTLFLAG_RD, NULL, "turnstile chain stats");
SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
"depth", CTLFLAG_RD, &turnstile_chains[i].tc_depth, 0,
NULL);
SYSCTL_ADD_UINT(NULL, SYSCTL_CHILDREN(chain_oid), OID_AUTO,
"max_depth", CTLFLAG_RD, &turnstile_chains[i].tc_max_depth,
0, NULL);
Unbreak mutex profiling (at least for me). o Always check for null when dereferencing the filename component. o Implement a try-and-backoff method for allocating memory to dump stats to avoid a spin-lock -> sleep-lock mutex lock order panic with WITNESS. Approved by: des, markm (mentor) Not objected: jhb
2003-02-25 22:28:46 +00:00
}
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
}
Oops, this didn't make it into my submit before I committed: Defer creation of the sysctl tree for the turnstile profiling stats until a SI_SUB_LOCK sysinit. Doing it in init_turnstiles() is too early as it is called before mi_startup().
2004-06-29 03:48:49 +00:00
SYSINIT(turnstile_profiling, SI_SUB_LOCK, SI_ORDER_ANY,
init_turnstile_profiling, NULL);
#endif
Mutex profiling code, conditional on the MUTEX_PROFILING option. Adds the following sysctl variables: debug.mutex.prof.enable enable / disable profiling debug.mutex.prof.acquisitions number of mutex acquisitions recorded debug.mutex.prof.records number of acquisition points recorded debug.mutex.prof.maxrecords max number of acquisition points debug.mutex.prof.rejected number of rejections (due to full table) debug.mutex.prof.hashsize hash size debug.mutex.prof.collisions number of hash collisions debug.mutex.prof.stats profiling statistics The code records four numbers for each acquisition point (identified by source file name and line number): longest time held, total time held, number of non-recursive acquisitions, average time held. The measurements are in clock cycles (as returned by get_cyclecount(9)); this may cause measurements on some SMP systems to be unreliable. This can probably be worked around by replacing get_cyclecount(9) by some incarnation of nanotime(9). This work was derived from initial patches by eivind.
2002-04-02 00:01:49 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
static void
init_turnstile0(void *dummy)
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
{
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
turnstile_zone = uma_zcreate("TURNSTILE", sizeof(struct turnstile),
- Reduce scope of #ifdef's in uma_zcreate() call in init_turnstile0(). - Set UMA_ZONE_NOFREE so that the per-turnstile spin locks are type stable to avoid a race where one thread might dereference a lock in a free'd turnstile that was previously used by another thread. Theorized by: tegge (2) MFC after: 1 week
2008-09-08 21:40:15 +00:00
NULL,
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
#ifdef INVARIANTS
- Reduce scope of #ifdef's in uma_zcreate() call in init_turnstile0(). - Set UMA_ZONE_NOFREE so that the per-turnstile spin locks are type stable to avoid a race where one thread might dereference a lock in a free'd turnstile that was previously used by another thread. Theorized by: tegge (2) MFC after: 1 week
2008-09-08 21:40:15 +00:00
turnstile_dtor,
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
#else
- Reduce scope of #ifdef's in uma_zcreate() call in init_turnstile0(). - Set UMA_ZONE_NOFREE so that the per-turnstile spin locks are type stable to avoid a race where one thread might dereference a lock in a free'd turnstile that was previously used by another thread. Theorized by: tegge (2) MFC after: 1 week
2008-09-08 21:40:15 +00:00
NULL,
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
#endif
- Reduce scope of #ifdef's in uma_zcreate() call in init_turnstile0(). - Set UMA_ZONE_NOFREE so that the per-turnstile spin locks are type stable to avoid a race where one thread might dereference a lock in a free'd turnstile that was previously used by another thread. Theorized by: tegge (2) MFC after: 1 week
2008-09-08 21:40:15 +00:00
turnstile_init, turnstile_fini, UMA_ALIGN_CACHE, UMA_ZONE_NOFREE);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
thread0.td_turnstile = turnstile_alloc();
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
}
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
SYSINIT(turnstile0, SI_SUB_LOCK, SI_ORDER_ANY, init_turnstile0, NULL);
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
/*
* Update a thread on the turnstile list after it's priority has been changed.
* The old priority is passed in as an argument.
*/
void
turnstile_adjust(struct thread *td, u_char oldpri)
{
struct turnstile *ts;
MPASS(TD_ON_LOCK(td));
/*
* Pick up the lock that td is blocked on.
*/
ts = td->td_blocked;
MPASS(ts != NULL);
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts. Sponsored by: Nokia
2008-02-07 06:55:38 +00:00
THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
/* Resort the turnstile on the list. */
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
if (!turnstile_adjust_thread(ts, td))
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
return;
/*
* If our priority was lowered and we are at the head of the
* turnstile, then propagate our new priority up the chain.
* Note that we currently don't try to revoke lent priorities
* when our priority goes up.
*/
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
MPASS(td->td_tsqueue == TS_EXCLUSIVE_QUEUE ||
td->td_tsqueue == TS_SHARED_QUEUE);
if (td == TAILQ_FIRST(&ts->ts_blocked[td->td_tsqueue]) &&
td->td_priority < oldpri) {
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
propagate_priority(td);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
}
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
}
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Set the owner of the lock this turnstile is attached to.
*/
static void
turnstile_setowner(struct turnstile *ts, struct thread *owner)
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
mtx_assert(&td_contested_lock, MA_OWNED);
MPASS(ts->ts_owner == NULL);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
/* A shared lock might not have an owner. */
if (owner == NULL)
return;
MPASS(owner->td_proc->p_magic == P_MAGIC);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
ts->ts_owner = owner;
LIST_INSERT_HEAD(&owner->td_contested, ts, ts_link);
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
}
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
#ifdef INVARIANTS
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
* UMA zone item deallocator.
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
*/
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
static void
turnstile_dtor(void *mem, int size, void *arg)
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile *ts;
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
ts = mem;
MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]));
MPASS(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]));
MPASS(TAILQ_EMPTY(&ts->ts_pending));
}
#endif
/*
* UMA zone item initializer.
*/
static int
turnstile_init(void *mem, int size, int flags)
{
struct turnstile *ts;
bzero(mem, size);
ts = mem;
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_INIT(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]);
TAILQ_INIT(&ts->ts_blocked[TS_SHARED_QUEUE]);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
TAILQ_INIT(&ts->ts_pending);
LIST_INIT(&ts->ts_free);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_init(&ts->ts_lock, "turnstile lock", NULL, MTX_SPIN | MTX_RECURSE);
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
return (0);
}
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
static void
turnstile_fini(void *mem, int size)
{
struct turnstile *ts;
ts = mem;
mtx_destroy(&ts->ts_lock);
}
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
/*
* Get a turnstile for a new thread.
*/
struct turnstile *
turnstile_alloc(void)
{
return (uma_zalloc(turnstile_zone, M_WAITOK));
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
}
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Free a turnstile when a thread is destroyed.
*/
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
void
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
turnstile_free(struct turnstile *ts)
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
{
- Convert turnstiles and sleepqueus to use UMA. This provides a modest speedup and will be more useful after each gains a spinlock in the impending thread_lock() commit. - Move initialization and asserts into init/fini routines. fini routines are only needed in the INVARIANTS case for now. Submitted by: Attilio Rao <attilio@FreeBSD.org> Tested by: kris, jeff
2007-05-18 06:32:24 +00:00
uma_zfree(turnstile_zone, ts);
- Switch from using save/disable/restore_intr to using critical_enter/exit and change the u_int mtx_saveintr member of struct mtx to a critical_t mtx_savecrit. - On the alpha we no longer need a custom _get_spin_lock() macro to avoid an extra PAL call, so remove it. - Partially fix using mutexes with WITNESS in modules. Change all the _mtx_{un,}lock_{spin,}_flags() macros to accept explicit file and line parameters and rename them to use a prefix of two underscores. Inside of kern_mutex.c, generate wrapper functions for _mtx_{un,}lock_{spin,}_flags() (only using a prefix of one underscore) that are called from modules. The macros mtx_{un,}lock_{spin,}_flags() are mapped to the __mtx_* macros inside of the kernel to inline the usual case of mutex operations and map to the internal _mtx_* functions in the module case so that modules will use WITNESS and KTR logging if the kernel is compiled with support for it.
2001-03-28 02:40:47 +00:00
}
Refine the turnstile and sleep queue interfaces just a bit: - Add a new _lock() call to each API that locks the associated chain lock for a lock_object pointer or wait channel. The _lookup() functions now require that the chain lock be locked via _lock() when they are called. - Change sleepq_add(), turnstile_wait() and turnstile_claim() to lookup the associated queue structure internally via _lookup() rather than accepting a pointer from the caller. For turnstiles, this means that the actual lookup of the turnstile in the hash table is only done when the thread actually blocks rather than being done on each loop iteration in _mtx_lock_sleep(). For sleep queues, this means that sleepq_lookup() is no longer used outside of the sleep queue code except to implement an assertion in cv_destroy(). - Change sleepq_broadcast() and sleepq_signal() to require that the chain lock is already required. For condition variables, this lets the cv_broadcast() and cv_signal() functions lock the sleep queue chain lock while testing the waiters count. This means that the waiters count internal to condition variables is no longer protected by the interlock mutex and cv_broadcast() and cv_signal() now no longer require that the interlock be held when they are called. This lets consumers of condition variables drop the lock before waking other threads which can result in fewer context switches. MFC after: 1 month
2004-10-12 18:36:20 +00:00
/*
* Lock the turnstile chain associated with the specified lock.
*/
void
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
turnstile_chain_lock(struct lock_object *lock)
Refine the turnstile and sleep queue interfaces just a bit: - Add a new _lock() call to each API that locks the associated chain lock for a lock_object pointer or wait channel. The _lookup() functions now require that the chain lock be locked via _lock() when they are called. - Change sleepq_add(), turnstile_wait() and turnstile_claim() to lookup the associated queue structure internally via _lookup() rather than accepting a pointer from the caller. For turnstiles, this means that the actual lookup of the turnstile in the hash table is only done when the thread actually blocks rather than being done on each loop iteration in _mtx_lock_sleep(). For sleep queues, this means that sleepq_lookup() is no longer used outside of the sleep queue code except to implement an assertion in cv_destroy(). - Change sleepq_broadcast() and sleepq_signal() to require that the chain lock is already required. For condition variables, this lets the cv_broadcast() and cv_signal() functions lock the sleep queue chain lock while testing the waiters count. This means that the waiters count internal to condition variables is no longer protected by the interlock mutex and cv_broadcast() and cv_signal() now no longer require that the interlock be held when they are called. This lets consumers of condition variables drop the lock before waking other threads which can result in fewer context switches. MFC after: 1 month
2004-10-12 18:36:20 +00:00
{
struct turnstile_chain *tc;
tc = TC_LOOKUP(lock);
mtx_lock_spin(&tc->tc_lock);
}
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
struct turnstile *
turnstile_trywait(struct lock_object *lock)
{
struct turnstile_chain *tc;
struct turnstile *ts;
tc = TC_LOOKUP(lock);
mtx_lock_spin(&tc->tc_lock);
LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash)
if (ts->ts_lockobj == lock) {
mtx_lock_spin(&ts->ts_lock);
return (ts);
}
ts = curthread->td_turnstile;
MPASS(ts != NULL);
mtx_lock_spin(&ts->ts_lock);
KASSERT(ts->ts_lockobj == NULL, ("stale ts_lockobj pointer"));
ts->ts_lockobj = lock;
return (ts);
}
void
turnstile_cancel(struct turnstile *ts)
{
struct turnstile_chain *tc;
struct lock_object *lock;
mtx_assert(&ts->ts_lock, MA_OWNED);
mtx_unlock_spin(&ts->ts_lock);
lock = ts->ts_lockobj;
if (ts == curthread->td_turnstile)
ts->ts_lockobj = NULL;
tc = TC_LOOKUP(lock);
mtx_unlock_spin(&tc->tc_lock);
}
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Look up the turnstile for a lock in the hash table locking the associated
Refine the turnstile and sleep queue interfaces just a bit: - Add a new _lock() call to each API that locks the associated chain lock for a lock_object pointer or wait channel. The _lookup() functions now require that the chain lock be locked via _lock() when they are called. - Change sleepq_add(), turnstile_wait() and turnstile_claim() to lookup the associated queue structure internally via _lookup() rather than accepting a pointer from the caller. For turnstiles, this means that the actual lookup of the turnstile in the hash table is only done when the thread actually blocks rather than being done on each loop iteration in _mtx_lock_sleep(). For sleep queues, this means that sleepq_lookup() is no longer used outside of the sleep queue code except to implement an assertion in cv_destroy(). - Change sleepq_broadcast() and sleepq_signal() to require that the chain lock is already required. For condition variables, this lets the cv_broadcast() and cv_signal() functions lock the sleep queue chain lock while testing the waiters count. This means that the waiters count internal to condition variables is no longer protected by the interlock mutex and cv_broadcast() and cv_signal() now no longer require that the interlock be held when they are called. This lets consumers of condition variables drop the lock before waking other threads which can result in fewer context switches. MFC after: 1 month
2004-10-12 18:36:20 +00:00
* turnstile chain along the way. If no turnstile is found in the hash
* table, NULL is returned.
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile *
turnstile_lookup(struct lock_object *lock)
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile_chain *tc;
struct turnstile *ts;
tc = TC_LOOKUP(lock);
Refine the turnstile and sleep queue interfaces just a bit: - Add a new _lock() call to each API that locks the associated chain lock for a lock_object pointer or wait channel. The _lookup() functions now require that the chain lock be locked via _lock() when they are called. - Change sleepq_add(), turnstile_wait() and turnstile_claim() to lookup the associated queue structure internally via _lookup() rather than accepting a pointer from the caller. For turnstiles, this means that the actual lookup of the turnstile in the hash table is only done when the thread actually blocks rather than being done on each loop iteration in _mtx_lock_sleep(). For sleep queues, this means that sleepq_lookup() is no longer used outside of the sleep queue code except to implement an assertion in cv_destroy(). - Change sleepq_broadcast() and sleepq_signal() to require that the chain lock is already required. For condition variables, this lets the cv_broadcast() and cv_signal() functions lock the sleep queue chain lock while testing the waiters count. This means that the waiters count internal to condition variables is no longer protected by the interlock mutex and cv_broadcast() and cv_signal() now no longer require that the interlock be held when they are called. This lets consumers of condition variables drop the lock before waking other threads which can result in fewer context switches. MFC after: 1 month
2004-10-12 18:36:20 +00:00
mtx_assert(&tc->tc_lock, MA_OWNED);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash)
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
if (ts->ts_lockobj == lock) {
mtx_lock_spin(&ts->ts_lock);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
return (ts);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
}
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
return (NULL);
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
}
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Unlock the turnstile chain associated with a given lock.
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
*/
void
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
turnstile_chain_unlock(struct lock_object *lock)
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile_chain *tc;
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
tc = TC_LOOKUP(lock);
mtx_unlock_spin(&tc->tc_lock);
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
}
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
/*
* Return a pointer to the thread waiting on this turnstile with the
* most important priority or NULL if the turnstile has no waiters.
*/
static struct thread *
turnstile_first_waiter(struct turnstile *ts)
{
struct thread *std, *xtd;
std = TAILQ_FIRST(&ts->ts_blocked[TS_SHARED_QUEUE]);
xtd = TAILQ_FIRST(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]);
if (xtd == NULL || (std != NULL && std->td_priority < xtd->td_priority))
return (std);
return (xtd);
}
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Take ownership of a turnstile and adjust the priority of the new
* owner appropriately.
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
*/
void
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
turnstile_claim(struct turnstile *ts)
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct thread *td, *owner;
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
struct turnstile_chain *tc;
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
MPASS(ts != curthread->td_turnstile);
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
owner = curthread;
mtx_lock_spin(&td_contested_lock);
turnstile_setowner(ts, owner);
mtx_unlock_spin(&td_contested_lock);
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
td = turnstile_first_waiter(ts);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(td != NULL);
MPASS(td->td_proc->p_magic == P_MAGIC);
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts. Sponsored by: Nokia
2008-02-07 06:55:38 +00:00
THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Update the priority of the new owner if needed.
*/
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_lock(owner);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
if (td->td_priority < owner->td_priority)
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
sched_lend_prio(owner, td->td_priority);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_unlock(owner);
tc = TC_LOOKUP(ts->ts_lockobj);
mtx_unlock_spin(&ts->ts_lock);
mtx_unlock_spin(&tc->tc_lock);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
}
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
/*
Refine the turnstile and sleep queue interfaces just a bit: - Add a new _lock() call to each API that locks the associated chain lock for a lock_object pointer or wait channel. The _lookup() functions now require that the chain lock be locked via _lock() when they are called. - Change sleepq_add(), turnstile_wait() and turnstile_claim() to lookup the associated queue structure internally via _lookup() rather than accepting a pointer from the caller. For turnstiles, this means that the actual lookup of the turnstile in the hash table is only done when the thread actually blocks rather than being done on each loop iteration in _mtx_lock_sleep(). For sleep queues, this means that sleepq_lookup() is no longer used outside of the sleep queue code except to implement an assertion in cv_destroy(). - Change sleepq_broadcast() and sleepq_signal() to require that the chain lock is already required. For condition variables, this lets the cv_broadcast() and cv_signal() functions lock the sleep queue chain lock while testing the waiters count. This means that the waiters count internal to condition variables is no longer protected by the interlock mutex and cv_broadcast() and cv_signal() now no longer require that the interlock be held when they are called. This lets consumers of condition variables drop the lock before waking other threads which can result in fewer context switches. MFC after: 1 month
2004-10-12 18:36:20 +00:00
* Block the current thread on the turnstile assicated with 'lock'. This
* function will context switch and not return until this thread has been
* woken back up. This function must be called with the appropriate
* turnstile chain locked and will return with it unlocked.
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
*/
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
void
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
turnstile_wait(struct turnstile *ts, struct thread *owner, int queue)
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile_chain *tc;
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
struct thread *td, *td1;
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
struct lock_object *lock;
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
KSE Milestone 2 Note ALL MODULES MUST BE RECOMPILED make the kernel aware that there are smaller units of scheduling than the process. (but only allow one thread per process at this time). This is functionally equivalent to teh previousl -current except that there is a thread associated with each process. Sorry john! (your next MFC will be a doosie!) Reviewed by: peter@freebsd.org, dillon@freebsd.org X-MFC after: ha ha ha ha
2001-09-12 08:38:13 +00:00
td = curthread;
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
if (owner)
MPASS(owner->td_proc->p_magic == P_MAGIC);
MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
Refine the turnstile and sleep queue interfaces just a bit: - Add a new _lock() call to each API that locks the associated chain lock for a lock_object pointer or wait channel. The _lookup() functions now require that the chain lock be locked via _lock() when they are called. - Change sleepq_add(), turnstile_wait() and turnstile_claim() to lookup the associated queue structure internally via _lookup() rather than accepting a pointer from the caller. For turnstiles, this means that the actual lookup of the turnstile in the hash table is only done when the thread actually blocks rather than being done on each loop iteration in _mtx_lock_sleep(). For sleep queues, this means that sleepq_lookup() is no longer used outside of the sleep queue code except to implement an assertion in cv_destroy(). - Change sleepq_broadcast() and sleepq_signal() to require that the chain lock is already required. For condition variables, this lets the cv_broadcast() and cv_signal() functions lock the sleep queue chain lock while testing the waiters count. This means that the waiters count internal to condition variables is no longer protected by the interlock mutex and cv_broadcast() and cv_signal() now no longer require that the interlock be held when they are called. This lets consumers of condition variables drop the lock before waking other threads which can result in fewer context switches. MFC after: 1 month
2004-10-12 18:36:20 +00:00
/*
* If the lock does not already have a turnstile, use this thread's
* turnstile. Otherwise insert the current thread into the
* turnstile already in use by this lock.
*/
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
tc = TC_LOOKUP(ts->ts_lockobj);
Always assert that the turnstile chain lock is held in turnstile_wait() and remove a duplicate hash lookup. MFC after: 1 week
2011-02-04 14:16:41 +00:00
mtx_assert(&tc->tc_lock, MA_OWNED);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
if (ts == td->td_turnstile) {
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#ifdef TURNSTILE_PROFILING
tc->tc_depth++;
if (tc->tc_depth > tc->tc_max_depth) {
tc->tc_max_depth = tc->tc_depth;
if (tc->tc_max_depth > turnstile_max_depth)
turnstile_max_depth = tc->tc_max_depth;
}
#endif
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
LIST_INSERT_HEAD(&tc->tc_turnstiles, ts, ts_hash);
KASSERT(TAILQ_EMPTY(&ts->ts_pending),
("thread's turnstile has pending threads"));
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]),
("thread's turnstile has exclusive waiters"));
KASSERT(TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]),
("thread's turnstile has shared waiters"));
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
KASSERT(LIST_EMPTY(&ts->ts_free),
("thread's turnstile has a non-empty free list"));
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
MPASS(ts->ts_lockobj != NULL);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
mtx_lock_spin(&td_contested_lock);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
turnstile_setowner(ts, owner);
mtx_unlock_spin(&td_contested_lock);
} else {
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_FOREACH(td1, &ts->ts_blocked[queue], td_lockq)
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
if (td1->td_priority > td->td_priority)
break;
mtx_lock_spin(&td_contested_lock);
if (td1 != NULL)
TAILQ_INSERT_BEFORE(td1, td, td_lockq);
else
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_INSERT_TAIL(&ts->ts_blocked[queue], td, td_lockq);
MPASS(owner == ts->ts_owner);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
mtx_unlock_spin(&td_contested_lock);
MPASS(td->td_turnstile != NULL);
LIST_INSERT_HEAD(&ts->ts_free, td->td_turnstile, ts_hash);
Add code to make default mutexes adaptive if the ADAPTIVE_MUTEXES kernel option is used (not on by default). - In the case of trying to lock a mutex, if the MTX_CONTESTED flag is set, then we can safely read the thread pointer from the mtx_lock member while holding sched_lock. We then examine the thread to see if it is currently executing on another CPU. If it is, then we keep looping instead of blocking. - In the case of trying to unlock a mutex, it is now possible for a mutex to have MTX_CONTESTED set in mtx_lock but to not have any threads actually blocked on it, so we need to handle that case. In that case, we just release the lock as if MTX_CONTESTED was not set and return. - We do not adaptively spin on Giant as Giant is held for long times and it slows SMP systems down to a crawl (it was taking several minutes, like 5-10 or so for my test alpha and sparc64 SMP boxes to boot up when they adaptively spinned on Giant). - We only compile in the code to do this for SMP kernels, it doesn't make sense for UP kernels. Tested on: i386, alpha, sparc64
2002-05-21 20:47:11 +00:00
}
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_lock(td);
thread_lock_set(td, &ts->ts_lock);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
td->td_turnstile = NULL;
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/* Save who we are blocked on and switch. */
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
lock = ts->ts_lockobj;
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
td->td_tsqueue = queue;
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
td->td_blocked = ts;
td->td_lockname = lock->lo_name;
Introduce the new kernel thread called "deadlock resolver". While the name is pretentious, a good explanation of its targets is reported in this 17 months old presentation e-mail: http://lists.freebsd.org/pipermail/freebsd-arch/2008-August/008452.html In order to implement it, the sq_type in sleepqueues is mandatory and not only compiled along with INVARIANTS option. Additively, a new sleepqueue function, sleepq_type() is added, returning the type of the sleepqueue linked to a wchan. Three new sysctls are added in order to configure the thread: debug.deadlkres.slptime_threshold debug.deadlkres.blktime_threshold debug.deadlkres.sleepfreq rappresenting the thresholds for sleep and block time that will lead to a deadlock matching (when exceeded), while the sleepfreq rappresents the number of seconds between 2 consecutive thread runnings. In order to enable the deadlock resolver thread recompile your kernel with the option DEADLKRES. Reviewed by: jeff Tested by: pho, Giovanni Trematerra Sponsored by: Nokia Incorporated, Sandvine Incorporated MFC after: 2 weeks
2010-01-09 01:46:38 +00:00
td->td_blktick = ticks;
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
TD_SET_LOCK(td);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_unlock_spin(&tc->tc_lock);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
propagate_priority(td);
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
if (LOCK_LOG_TEST(lock, 0))
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
CTR4(KTR_LOCK, "%s: td %d blocked on [%p] %s", __func__,
td->td_tid, lock, lock->lo_name);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Implement the DTrace sched provider. This implementation aims to be compatible with the sched provider implemented by Solaris and its open- source derivatives. Full documentation of the sched provider can be found on Oracle's DTrace wiki pages. Note that for compatibility with scripts originally written for Solaris, serveral probes are defined that will never fire. These probes are defined to fire when Solaris-specific features perform certain actions. As these features are not present in FreeBSD, the probes can never fire. Also, I have added a two probes that are not defined in Solaris, lend-pri and load-change. These probes have been added to make it possible to collect schedgraph data with DTrace. Finally, a few probes are defined in Solaris to take a cpuinfo_t * argument. As it was not immediately clear to me how to translate that to FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *. Sponsored by: Sandvine Incorporated MFC after: 2 weeks
2012-05-15 01:30:25 +00:00
SDT_PROBE0(sched, , , sleep);
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts. Sponsored by: Nokia
2008-02-07 06:55:38 +00:00
THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
- Make SCHED_STATS more generic by adding a wrapper to create the variables and sysctl nodes. - In reset walk the children of kern_sched_stats and reset the counters via the oid_arg1 pointer. This allows us to add arbitrary counters to the tree and still reset them properly. - Define a set of switch types to be passed with flags to mi_switch(). These types are named SWT_*. These types correspond to SCHED_STATS counters and are automatically handled in this way. - Make the new SWT_ types more specific than the older switch stats. There are now stats for idle switches, remote idle wakeups, remote preemption ithreads idling, etc. - Add switch statistics for ULE's pickcpu algorithm. These stats include how much migration there is, how often affinity was successful, how often threads were migrated to the local cpu on wakeup, etc. Sponsored by: Nokia
2008-04-17 04:20:10 +00:00
mi_switch(SW_VOL | SWT_TURNSTILE, NULL);
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
if (LOCK_LOG_TEST(lock, 0))
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
CTR4(KTR_LOCK, "%s: td %d free from blocked on [%p] %s",
__func__, td->td_tid, lock, lock->lo_name);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_unlock(td);
Move most of sys/mutex.h into kern/kern_mutex.c, thereby making the mutex inline functions non-inlined. Hide parts of the mutex implementation that should not be exposed. Make sure that WITNESS code is not executed during boot until the mutexes are fully initialized by SI_SUB_MUTEX (the original motivation for this commit). Submitted by: peter
2001-01-21 22:34:43 +00:00
}
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Pick the highest priority thread on this turnstile and put it on the
* pending list. This must be called with the turnstile chain locked.
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
int
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
turnstile_signal(struct turnstile *ts, int queue)
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
{
struct turnstile_chain *tc;
struct thread *td;
int empty;
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(ts != NULL);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(curthread->td_proc->p_magic == P_MAGIC);
Adaptive spinning in write path with readers and writer starvation avoidance. - Move recursion checking into rwlock inlines to free a bit for use with adaptive spinners. - Clear the RW_LOCK_WRITE_SPINNERS flag whenever the lock state changes causing write spinners to restart their loop. - Write spinners are limited by a count while readers hold the lock as there is no way to know for certain whether readers are running still. - In the read path block if there are write waiters or spinners to avoid starving writers. Use a new per-thread count, td_rw_rlocks, to skip starvation avoidance if it might cause a deadlock. - Remove or change invalid assertions in turnstiles. Reviewed by: attilio (developed parts of the patch as well) Sponsored by: Nokia
2008-02-06 01:02:13 +00:00
MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Pick the highest priority thread blocked on this lock and
* move it to the pending list.
*/
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
td = TAILQ_FIRST(&ts->ts_blocked[queue]);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(td->td_proc->p_magic == P_MAGIC);
mtx_lock_spin(&td_contested_lock);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_REMOVE(&ts->ts_blocked[queue], td, td_lockq);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
mtx_unlock_spin(&td_contested_lock);
TAILQ_INSERT_TAIL(&ts->ts_pending, td, td_lockq);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Force a commit on kern_mutex.c to explain reason for last commit but while I'm at it also add a comment in mtx_validate() explaining the purpose of the last change. Basically, this fixes booting kernels compiled with MUTEX_DEBUG. What used to happen is before we setidt from init386() [still using BTX idt], we called mtx_init() on several mutex locks, notably Giant and some others. This is a problem for MUTEX_DEBUG because it enables mtx_validate() which calls kernacc(), some of which in turn requires Giant. Fix by calling kernacc() from mtx_validate() only if (!cold).
2001-08-24 23:00:59 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* If the turnstile is now empty, remove it from its chain and
* give it to the about-to-be-woken thread. Otherwise take a
* turnstile from the free list and give it to the thread.
Whitespace cleanup.
2002-10-23 10:26:54 +00:00
*/
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
empty = TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) &&
TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]);
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
if (empty) {
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
tc = TC_LOOKUP(ts->ts_lockobj);
mtx_assert(&tc->tc_lock, MA_OWNED);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(LIST_EMPTY(&ts->ts_free));
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#ifdef TURNSTILE_PROFILING
tc->tc_depth--;
#endif
} else
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
ts = LIST_FIRST(&ts->ts_free);
Assert that the we never give a thread a NULL turnstile when waking it up.
2003-12-09 21:09:54 +00:00
MPASS(ts != NULL);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
LIST_REMOVE(ts, ts_hash);
td->td_turnstile = ts;
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
return (empty);
}
- Add MTX_SYSINIT and SX_SYSINIT as macro glue for allowing sx and mtx locks to be able to setup a SYSINIT call. This helps in places where a lock is needed to protect some data, but the data is not truly associated with a subsystem that can properly initialize it's lock. The macros use the mtx_sysinit() and sx_sysinit() functions, respectively, as the handler argument to SYSINIT(). Reviewed by: alfred, jhb, smp@
2002-04-02 16:05:43 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Put all blocked threads on the pending list. This must be called with
* the turnstile chain locked.
- Add MTX_SYSINIT and SX_SYSINIT as macro glue for allowing sx and mtx locks to be able to setup a SYSINIT call. This helps in places where a lock is needed to protect some data, but the data is not truly associated with a subsystem that can properly initialize it's lock. The macros use the mtx_sysinit() and sx_sysinit() functions, respectively, as the handler argument to SYSINIT(). Reviewed by: alfred, jhb, smp@
2002-04-02 16:05:43 +00:00
*/
void
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
turnstile_broadcast(struct turnstile *ts, int queue)
- Add MTX_SYSINIT and SX_SYSINIT as macro glue for allowing sx and mtx locks to be able to setup a SYSINIT call. This helps in places where a lock is needed to protect some data, but the data is not truly associated with a subsystem that can properly initialize it's lock. The macros use the mtx_sysinit() and sx_sysinit() functions, respectively, as the handler argument to SYSINIT(). Reviewed by: alfred, jhb, smp@
2002-04-02 16:05:43 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct turnstile_chain *tc;
struct turnstile *ts1;
struct thread *td;
- Add MTX_SYSINIT and SX_SYSINIT as macro glue for allowing sx and mtx locks to be able to setup a SYSINIT call. This helps in places where a lock is needed to protect some data, but the data is not truly associated with a subsystem that can properly initialize it's lock. The macros use the mtx_sysinit() and sx_sysinit() functions, respectively, as the handler argument to SYSINIT(). Reviewed by: alfred, jhb, smp@
2002-04-02 16:05:43 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(ts != NULL);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(curthread->td_proc->p_magic == P_MAGIC);
Adaptive spinning in write path with readers and writer starvation avoidance. - Move recursion checking into rwlock inlines to free a bit for use with adaptive spinners. - Clear the RW_LOCK_WRITE_SPINNERS flag whenever the lock state changes causing write spinners to restart their loop. - Write spinners are limited by a count while readers hold the lock as there is no way to know for certain whether readers are running still. - In the read path block if there are write waiters or spinners to avoid starving writers. Use a new per-thread count, td_rw_rlocks, to skip starvation avoidance if it might cause a deadlock. - Remove or change invalid assertions in turnstiles. Reviewed by: attilio (developed parts of the patch as well) Sponsored by: Nokia
2008-02-06 01:02:13 +00:00
MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
/*
* We must have the chain locked so that we can remove the empty
* turnstile from the hash queue.
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
tc = TC_LOOKUP(ts->ts_lockobj);
mtx_assert(&tc->tc_lock, MA_OWNED);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Transfer the blocked list to the pending list.
*/
mtx_lock_spin(&td_contested_lock);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
TAILQ_CONCAT(&ts->ts_pending, &ts->ts_blocked[queue], td_lockq);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
mtx_unlock_spin(&td_contested_lock);
- Add MTX_SYSINIT and SX_SYSINIT as macro glue for allowing sx and mtx locks to be able to setup a SYSINIT call. This helps in places where a lock is needed to protect some data, but the data is not truly associated with a subsystem that can properly initialize it's lock. The macros use the mtx_sysinit() and sx_sysinit() functions, respectively, as the handler argument to SYSINIT(). Reviewed by: alfred, jhb, smp@
2002-04-02 16:05:43 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Give a turnstile to each thread. The last thread gets
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
* this turnstile if the turnstile is empty.
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
*/
TAILQ_FOREACH(td, &ts->ts_pending, td_lockq) {
if (LIST_EMPTY(&ts->ts_free)) {
MPASS(TAILQ_NEXT(td, td_lockq) == NULL);
ts1 = ts;
Add two new kernel options to allow rudimentary profiling of the internal hash tables used in the sleep queue and turnstile code. Each option adds a sysctl tree under debug containing the maximum depth of any bucket in the hash table as well as a separate node for each bucket (or chain) containing the current depth and maximum depth for that bucket.
2004-06-29 02:30:12 +00:00
#ifdef TURNSTILE_PROFILING
tc->tc_depth--;
#endif
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
} else
ts1 = LIST_FIRST(&ts->ts_free);
Assert that the we never give a thread a NULL turnstile when waking it up.
2003-12-09 21:09:54 +00:00
MPASS(ts1 != NULL);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
LIST_REMOVE(ts1, ts_hash);
td->td_turnstile = ts1;
}
}
- Close a race where a thread on another CPU could release a contested lock and empty its turnstile while the blocking threads still pointed to the turnstile. If the thread on the first CPU blocked on a lock owned by one of the threads blocked on the turnstile just woken up, then the first CPU could try to manipulate a bogus thread queue in the turnstile during priority propagation. - Update locking notes for ts_owner and always clear ts_owner, not just under INVARIANTS. Tested by: sam (1)
2003-11-12 23:48:42 +00:00
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Wakeup all threads on the pending list and adjust the priority of the
* current thread appropriately. This must be called with the turnstile
* chain locked.
Whitespace cleanup.
2002-10-23 10:26:54 +00:00
*/
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
void
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
turnstile_unpend(struct turnstile *ts, int owner_type)
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
TAILQ_HEAD( ,thread) pending_threads;
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
struct turnstile *nts;
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct thread *td;
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
u_char cp, pri;
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(ts != NULL);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
Adaptive spinning in write path with readers and writer starvation avoidance. - Move recursion checking into rwlock inlines to free a bit for use with adaptive spinners. - Clear the RW_LOCK_WRITE_SPINNERS flag whenever the lock state changes causing write spinners to restart their loop. - Write spinners are limited by a count while readers hold the lock as there is no way to know for certain whether readers are running still. - In the read path block if there are write waiters or spinners to avoid starving writers. Use a new per-thread count, td_rw_rlocks, to skip starvation avoidance if it might cause a deadlock. - Remove or change invalid assertions in turnstiles. Reviewed by: attilio (developed parts of the patch as well) Sponsored by: Nokia
2008-02-06 01:02:13 +00:00
MPASS(ts->ts_owner == curthread || ts->ts_owner == NULL);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(!TAILQ_EMPTY(&ts->ts_pending));
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Move the list of pending threads out of the turnstile and
* into a local variable.
*/
TAILQ_INIT(&pending_threads);
TAILQ_CONCAT(&pending_threads, &ts->ts_pending, td_lockq);
#ifdef INVARIANTS
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
if (TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) &&
TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]))
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
ts->ts_lockobj = NULL;
Split the WITNESS and MUTEX_DEBUG options apart so that WITNESS does not depend on MUTEX_DEBUG. The MUTEX_DEBUG option turns on extra assertions and checks to verify that mutexes themselves are implemented properly. The WITNESS option uses extra checks and diagnostics to verify that other code is using mutexes properly.
2000-12-01 00:10:59 +00:00
#endif
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
/*
* Adjust the priority of curthread based on other contested
* locks it owns. Don't lower the priority below the base
* priority however.
*/
td = curthread;
pri = PRI_MAX;
thread_lock(td);
mtx_lock_spin(&td_contested_lock);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Remove the turnstile from this thread's list of contested locks
* since this thread doesn't own it anymore. New threads will
* not be blocking on the turnstile until it is claimed by a new
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
* owner. There might not be a current owner if this is a shared
* lock.
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
*/
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
if (ts->ts_owner != NULL) {
ts->ts_owner = NULL;
LIST_REMOVE(ts, ts_link);
}
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
LIST_FOREACH(nts, &td->td_contested, ts_link) {
cp = turnstile_first_waiter(nts)->td_priority;
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
if (cp < pri)
pri = cp;
}
mtx_unlock_spin(&td_contested_lock);
Rework the interface between priority propagation (lending) and the schedulers a bit to ensure more correct handling of priorities and fewer priority inversions: - Add two functions to the sched(9) API to handle priority lending: sched_lend_prio() and sched_unlend_prio(). The turnstile code uses these functions to ask the scheduler to lend a thread a set priority and to tell the scheduler when it thinks it is ok for a thread to stop borrowing priority. The unlend case is slightly complex in that the turnstile code tells the scheduler what the minimum priority of the thread needs to be to satisfy the requirements of any other threads blocked on locks owned by the thread in question. The scheduler then decides where the thread can go back to normal mode (if it's normal priority is high enough to satisfy the pending lock requests) or it it should continue to use the priority specified to the sched_unlend_prio() call. This involves adding a new per-thread flag TDF_BORROWING that replaces the ULE-only kse flag for priority elevation. - Schedulers now refuse to lower the priority of a thread that is currently borrowing another therad's priority. - If a scheduler changes the priority of a thread that is currently sitting on a turnstile, it will call a new function turnstile_adjust() to inform the turnstile code of the change. This function resorts the thread on the priority list of the turnstile if needed, and if the thread ends up at the head of the list (due to having the highest priority) and its priority was raised, then it will propagate that new priority to the owner of the lock it is blocked on. Some additional fixes specific to the 4BSD scheduler include: - Common code for updating the priority of a thread when the user priority of its associated kse group has been consolidated in a new static function resetpriority_thread(). One change to this function is that it will now only adjust the priority of a thread if it already has a time sharing priority, thus preserving any boosts from a tsleep() until the thread returns to userland. Also, resetpriority() no longer calls maybe_resched() on each thread in the group. Instead, the code calling resetpriority() is responsible for calling resetpriority_thread() on any threads that need to be updated. - schedcpu() now uses resetpriority_thread() instead of just calling sched_prio() directly after it updates a kse group's user priority. - sched_clock() now uses resetpriority_thread() rather than writing directly to td_priority. - sched_nice() now updates all the priorities of the threads after the group priority has been adjusted. Discussed with: bde Reviewed by: ups, jeffr Tested on: 4bsd, ule Tested on: i386, alpha, sparc64
2004-12-30 20:52:44 +00:00
sched_unlend_prio(td, pri);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_unlock(td);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
/*
* Wake up all the pending threads. If a thread is not blocked
* on a lock, then it is currently executing on another CPU in
Adjust an assertion for the TDF_TSNOBLOCK race handling in turnstile_unpend(). A racing thread that does not have TDI_LOCK set may either be running on another CPU or it may be sitting on a run queue if it was preempted during the very small window in turnstile_wait() between unlocking the turnstile chain lock and locking sched_lock.
2003-12-09 21:14:31 +00:00
* turnstile_wait() or sitting on a run queue waiting to resume
* in turnstile_wait(). Set a flag to force it to try to acquire
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* the lock again instead of blocking.
*/
while (!TAILQ_EMPTY(&pending_threads)) {
td = TAILQ_FIRST(&pending_threads);
TAILQ_REMOVE(&pending_threads, td, td_lockq);
Implement the DTrace sched provider. This implementation aims to be compatible with the sched provider implemented by Solaris and its open- source derivatives. Full documentation of the sched provider can be found on Oracle's DTrace wiki pages. Note that for compatibility with scripts originally written for Solaris, serveral probes are defined that will never fire. These probes are defined to fire when Solaris-specific features perform certain actions. As these features are not present in FreeBSD, the probes can never fire. Also, I have added a two probes that are not defined in Solaris, lend-pri and load-change. These probes have been added to make it possible to collect schedgraph data with DTrace. Finally, a few probes are defined in Solaris to take a cpuinfo_t * argument. As it was not immediately clear to me how to translate that to FreeBSD, currently those probes are passed NULL in place of a cpuinfo_t *. Sponsored by: Sandvine Incorporated MFC after: 2 weeks
2012-05-15 01:30:25 +00:00
SDT_PROBE2(sched, , , wakeup, td, td->td_proc);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_lock(td);
- Add THREAD_LOCKPTR_ASSERT() to assert that the thread's lock points at the provided lock or &blocked_lock. The thread may be temporarily assigned to the blocked_lock by the scheduler so a direct comparison can not always be made. - Use THREAD_LOCKPTR_ASSERT() in the primary consumers of the scheduling interfaces. The schedulers themselves still use more explicit asserts. Sponsored by: Nokia
2008-02-07 06:55:38 +00:00
THREAD_LOCKPTR_ASSERT(td, &ts->ts_lock);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(td->td_proc->p_magic == P_MAGIC);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
MPASS(TD_ON_LOCK(td));
TD_CLR_LOCK(td);
MPASS(TD_CAN_RUN(td));
td->td_blocked = NULL;
td->td_lockname = NULL;
Introduce the new kernel thread called "deadlock resolver". While the name is pretentious, a good explanation of its targets is reported in this 17 months old presentation e-mail: http://lists.freebsd.org/pipermail/freebsd-arch/2008-August/008452.html In order to implement it, the sq_type in sleepqueues is mandatory and not only compiled along with INVARIANTS option. Additively, a new sleepqueue function, sleepq_type() is added, returning the type of the sleepqueue linked to a wchan. Three new sysctls are added in order to configure the thread: debug.deadlkres.slptime_threshold debug.deadlkres.blktime_threshold debug.deadlkres.sleepfreq rappresenting the thresholds for sleep and block time that will lead to a deadlock matching (when exceeded), while the sleepfreq rappresents the number of seconds between 2 consecutive thread runnings. In order to enable the deadlock resolver thread recompile your kernel with the option DEADLKRES. Reviewed by: jeff Tested by: pho, Giovanni Trematerra Sponsored by: Nokia Incorporated, Sandvine Incorporated MFC after: 2 weeks
2010-01-09 01:46:38 +00:00
td->td_blktick = 0;
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
#ifdef INVARIANTS
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
td->td_tsqueue = 0xff;
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
#endif
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
sched_add(td, SRQ_BORING);
thread_unlock(td);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
}
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_unlock_spin(&ts->ts_lock);
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
}
- Bring back turnstile_empty() which can check to see if an individual queue on a turnstile is empty. - Add a turnstile_disown() function that allows a thread to give up ownership of a turnstile w/o waking up any waiters.
2006-04-18 18:16:54 +00:00
/*
* Give up ownership of a turnstile. This must be called with the
* turnstile chain locked.
*/
void
turnstile_disown(struct turnstile *ts)
{
struct thread *td;
u_char cp, pri;
MPASS(ts != NULL);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
- Bring back turnstile_empty() which can check to see if an individual queue on a turnstile is empty. - Add a turnstile_disown() function that allows a thread to give up ownership of a turnstile w/o waking up any waiters.
2006-04-18 18:16:54 +00:00
MPASS(ts->ts_owner == curthread);
MPASS(TAILQ_EMPTY(&ts->ts_pending));
MPASS(!TAILQ_EMPTY(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE]) ||
!TAILQ_EMPTY(&ts->ts_blocked[TS_SHARED_QUEUE]));
/*
* Remove the turnstile from this thread's list of contested locks
* since this thread doesn't own it anymore. New threads will
* not be blocking on the turnstile until it is claimed by a new
* owner.
*/
mtx_lock_spin(&td_contested_lock);
ts->ts_owner = NULL;
LIST_REMOVE(ts, ts_link);
mtx_unlock_spin(&td_contested_lock);
/*
* Adjust the priority of curthread based on other contested
* locks it owns. Don't lower the priority below the base
* priority however.
*/
td = curthread;
pri = PRI_MAX;
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_lock(td);
mtx_unlock_spin(&ts->ts_lock);
- Bring back turnstile_empty() which can check to see if an individual queue on a turnstile is empty. - Add a turnstile_disown() function that allows a thread to give up ownership of a turnstile w/o waking up any waiters.
2006-04-18 18:16:54 +00:00
mtx_lock_spin(&td_contested_lock);
LIST_FOREACH(ts, &td->td_contested, ts_link) {
cp = turnstile_first_waiter(ts)->td_priority;
if (cp < pri)
pri = cp;
}
mtx_unlock_spin(&td_contested_lock);
sched_unlend_prio(td, pri);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
thread_unlock(td);
- Bring back turnstile_empty() which can check to see if an individual queue on a turnstile is empty. - Add a turnstile_disown() function that allows a thread to give up ownership of a turnstile w/o waking up any waiters.
2006-04-18 18:16:54 +00:00
}
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
/*
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
* Return the first thread in a turnstile.
Change and clean the mutex lock interface. mtx_enter(lock, type) becomes: mtx_lock(lock) for sleep locks (MTX_DEF-initialized locks) mtx_lock_spin(lock) for spin locks (MTX_SPIN-initialized) similarily, for releasing a lock, we now have: mtx_unlock(lock) for MTX_DEF and mtx_unlock_spin(lock) for MTX_SPIN. We change the caller interface for the two different types of locks because the semantics are entirely different for each case, and this makes it explicitly clear and, at the same time, it rids us of the extra `type' argument. The enter->lock and exit->unlock change has been made with the idea that we're "locking data" and not "entering locked code" in mind. Further, remove all additional "flags" previously passed to the lock acquire/release routines with the exception of two: MTX_QUIET and MTX_NOSWITCH The functionality of these flags is preserved and they can be passed to the lock/unlock routines by calling the corresponding wrappers: mtx_{lock, unlock}_flags(lock, flag(s)) and mtx_{lock, unlock}_spin_flags(lock, flag(s)) for MTX_DEF and MTX_SPIN locks, respectively. Re-inline some lock acq/rel code; in the sleep lock case, we only inline the _obtain_lock()s in order to ensure that the inlined code fits into a cache line. In the spin lock case, we inline recursion and actually only perform a function call if we need to spin. This change has been made with the idea that we generally tend to avoid spin locks and that also the spin locks that we do have and are heavily used (i.e. sched_lock) do recurse, and therefore in an effort to reduce function call overhead for some architectures (such as alpha), we inline recursion for this case. Create a new malloc type for the witness code and retire from using the M_DEV type. The new type is called M_WITNESS and is only declared if WITNESS is enabled. Begin cleaning up some machdep/mutex.h code - specifically updated the "optimized" inlined code in alpha/mutex.h and wrote MTX_LOCK_SPIN and MTX_UNLOCK_SPIN asm macros for the i386/mutex.h as we presently need those. Finally, caught up to the interface changes in all sys code. Contributors: jake, jhb, jasone (in no particular order)
2001-02-09 06:11:45 +00:00
*/
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
struct thread *
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
turnstile_head(struct turnstile *ts, int queue)
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
{
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
#ifdef INVARIANTS
- Make the mutex code almost completely machine independent. This greatly reducues the maintenance load for the mutex code. The only MD portions of the mutex code are in machine/mutex.h now, which include the assembly macros for handling mutexes as well as optionally overriding the mutex micro-operations. For example, we use optimized micro-ops on the x86 platform #ifndef I386_CPU. - Change the behavior of the SMP_DEBUG kernel option. In the new code, mtx_assert() only depends on INVARIANTS, allowing other kernel developers to have working mutex assertiions without having to include all of the mutex debugging code. The SMP_DEBUG kernel option has been renamed to MUTEX_DEBUG and now just controls extra mutex debugging code. - Abolish the ugly mtx_f hack. Instead, we dynamically allocate seperate mtx_debug structures on the fly in mtx_init, except for mutexes that are initiated very early in the boot process. These mutexes are declared using a special MUTEX_DECLARE() macro, and use a new flag MTX_COLD when calling mtx_init. This is still somewhat hackish, but it is less evil than the mtx_f filler struct, and the mtx struct is now the same size with and without mutex debugging code. - Add some micro-micro-operation macros for doing the actual atomic operations on the mutex mtx_lock field to make it easier for other archs to override/optimize mutex ops if needed. These new tiny ops also clean up the code in some places by replacing long atomic operation function calls that spanned 2-3 lines with a short 1-line macro call. - Don't call mi_switch() from mtx_enter_hard() when we block while trying to obtain a sleep mutex. Calling mi_switch() would bogusly release Giant before switching to the next process. Instead, inline most of the code from mi_switch() in the mtx_enter_hard() function. Note that when we finally kill Giant we can back this out and go back to calling mi_switch().
2000-10-20 07:26:37 +00:00
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
MPASS(ts != NULL);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
Add an implementation of turnstiles and change the sleep mutex code to use turnstiles to implement blocking isntead of implementing a thread queue directly. These turnstiles are somewhat similar to those used in Solaris 7 as described in Solaris Internals but are also different. Turnstiles do not come out of a fixed-sized pool. Rather, each thread is assigned a turnstile when it is created that it frees when it is destroyed. When a thread blocks on a lock, it donates its turnstile to that lock to serve as queue of blocked threads. The queue associated with a given lock is found by a lookup in a simple hash table. The turnstile itself is protected by a lock associated with its entry in the hash table. This means that sched_lock is no longer needed to contest on a mutex. Instead, sched_lock is only used when manipulating run queues or thread priorities. Turnstiles also implement priority propagation inherently. Currently turnstiles only support mutexes. Eventually, however, turnstiles may grow two queue's to support a non-sleepable reader/writer lock implementation. For more details, see the comments in sys/turnstile.h and kern/subr_turnstile.c. The two primary advantages from the turnstile code include: 1) the size of struct mutex shrinks by four pointers as it no longer stores the thread queue linkages directly, and 2) less contention on sched_lock in SMP systems including the ability for multiple CPUs to contend on different locks simultaneously (not that this last detail is necessarily that much of a big win). Note that 1) means that this commit is a kernel ABI breaker, so don't mix old modules with a new kernel and vice versa. Tested on: i386 SMP, sparc64 SMP, alpha SMP
2003-11-11 22:07:29 +00:00
#endif
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
return (TAILQ_FIRST(&ts->ts_blocked[queue]));
}
- Bring back turnstile_empty() which can check to see if an individual queue on a turnstile is empty. - Add a turnstile_disown() function that allows a thread to give up ownership of a turnstile w/o waking up any waiters.
2006-04-18 18:16:54 +00:00
/*
* Returns true if a sub-queue of a turnstile is empty.
*/
int
turnstile_empty(struct turnstile *ts, int queue)
{
#ifdef INVARIANTS
MPASS(ts != NULL);
MPASS(queue == TS_SHARED_QUEUE || queue == TS_EXCLUSIVE_QUEUE);
Commit 3/14 of sched_lock decomposition. - Add a per-turnstile spinlock to solve potential priority propagation deadlocks that are possible with thread_lock(). - The turnstile lock order is defined as the exact opposite of the lock order used with the sleep locks they represent. This allows us to walk in reverse order in priority_propagate and this is the only place we wish to multiply acquire turnstile locks. - Use the turnstile_chain lock to protect assigning mutexes to turnstiles. - Change the turnstile interface to pass back turnstile pointers to the consumers. This allows us to reduce some locking and makes it easier to cancel turnstile assignment while the turnstile chain lock is held. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
mtx_assert(&ts->ts_lock, MA_OWNED);
- Bring back turnstile_empty() which can check to see if an individual queue on a turnstile is empty. - Add a turnstile_disown() function that allows a thread to give up ownership of a turnstile w/o waking up any waiters.
2006-04-18 18:16:54 +00:00
#endif
return (TAILQ_EMPTY(&ts->ts_blocked[queue]));
}
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
#ifdef DDB
static void
print_thread(struct thread *td, const char *prefix)
{
db_printf("%s%p (tid %d, pid %d, \"%s\")\n", prefix, td, td->td_tid,
Finish r173600. There is no need to test a condition if both cases result in the same value. Found by: PVS-Studio Sponsored by: The FreeBSD Foundation MFC after: 1 week
2016-02-10 21:16:37 +00:00
td->td_proc->p_pid, td->td_name);
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
}
static void
print_queue(struct threadqueue *queue, const char *header, const char *prefix)
{
struct thread *td;
db_printf("%s:\n", header);
if (TAILQ_EMPTY(queue)) {
db_printf("%sempty\n", prefix);
return;
}
TAILQ_FOREACH(td, queue, td_lockq) {
print_thread(td, prefix);
}
Major update to the way synchronization is done in the kernel. Highlights include: * Mutual exclusion is used instead of spl*(). See mutex(9). (Note: The alpha port is still in transition and currently uses both.) * Per-CPU idle processes. * Interrupts are run in their own separate kernel threads and can be preempted (i386 only). Partially contributed by: BSDi (BSD/OS) Submissions by (at least): cp, dfr, dillon, grog, jake, jhb, sheldonh
2000-09-07 01:33:02 +00:00
}
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
DB_SHOW_COMMAND(turnstile, db_show_turnstile)
{
struct turnstile_chain *tc;
struct turnstile *ts;
struct lock_object *lock;
int i;
if (!have_addr)
return;
/*
* First, see if there is an active turnstile for the lock indicated
* by the address.
*/
lock = (struct lock_object *)addr;
tc = TC_LOOKUP(lock);
LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash)
if (ts->ts_lockobj == lock)
goto found;
/*
* Second, see if there is an active turnstile at the address
* indicated.
*/
for (i = 0; i < TC_TABLESIZE; i++)
LIST_FOREACH(ts, &turnstile_chains[i].tc_turnstiles, ts_hash) {
if (ts == (struct turnstile *)addr)
goto found;
}
db_printf("Unable to locate a turnstile via %p\n", (void *)addr);
return;
found:
lock = ts->ts_lockobj;
db_printf("Lock: %p - (%s) %s\n", lock, LOCK_CLASS(lock)->lc_name,
lock->lo_name);
if (ts->ts_owner)
print_thread(ts->ts_owner, "Lock Owner: ");
else
db_printf("Lock Owner: none\n");
print_queue(&ts->ts_blocked[TS_SHARED_QUEUE], "Shared Waiters", "\t");
print_queue(&ts->ts_blocked[TS_EXCLUSIVE_QUEUE], "Exclusive Waiters",
"\t");
print_queue(&ts->ts_pending, "Pending Threads", "\t");
}
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
Rename 'show lockchain' to 'show locktree' and 'show threadchain' to 'show lockchain'. The churn is because I'm about to add a new 'show sleepchain' similar to 'show lockchain' for sleep locks (lockmgr and sx) and 'show threadchain' was a bit ambiguous as both commands show a chain of thread dependencies, 'lockchain' is for non-sleepable locks (mtx and rw) and 'sleepchain' is for sleepable locks.
2006-08-15 16:44:18 +00:00
/*
* Show all the threads a particular thread is waiting on based on
* non-sleepable and non-spin locks.
*/
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
static void
Rename 'show lockchain' to 'show locktree' and 'show threadchain' to 'show lockchain'. The churn is because I'm about to add a new 'show sleepchain' similar to 'show lockchain' for sleep locks (lockmgr and sx) and 'show threadchain' was a bit ambiguous as both commands show a chain of thread dependencies, 'lockchain' is for non-sleepable locks (mtx and rw) and 'sleepchain' is for sleepable locks.
2006-08-15 16:44:18 +00:00
print_lockchain(struct thread *td, const char *prefix)
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
{
struct lock_object *lock;
struct lock_class *class;
struct turnstile *ts;
/*
* Follow the chain. We keep walking as long as the thread is
* blocked on a turnstile that has an owner.
*/
Honor db_pager_quit in 'show threadchain', 'show allchains', and 'show lockchain'. This is especially helpful for the first 2 as a threadchain could get stuck in an infinite loop during a mutex deadlock.
2006-07-12 21:25:24 +00:00
while (!db_pager_quit) {
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
db_printf("%sthread %d (pid %d, %s) ", prefix, td->td_tid,
Finish r173600. There is no need to test a condition if both cases result in the same value. Found by: PVS-Studio Sponsored by: The FreeBSD Foundation MFC after: 1 week
2016-02-10 21:16:37 +00:00
td->td_proc->p_pid, td->td_name);
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
switch (td->td_state) {
case TDS_INACTIVE:
db_printf("is inactive\n");
return;
case TDS_CAN_RUN:
db_printf("can run\n");
return;
case TDS_RUNQ:
db_printf("is on a run queue\n");
return;
case TDS_RUNNING:
db_printf("running on CPU %d\n", td->td_oncpu);
return;
case TDS_INHIBITED:
if (TD_ON_LOCK(td)) {
ts = td->td_blocked;
lock = ts->ts_lockobj;
class = LOCK_CLASS(lock);
db_printf("blocked on lock %p (%s) \"%s\"\n",
lock, class->lc_name, lock->lo_name);
if (ts->ts_owner == NULL)
return;
td = ts->ts_owner;
break;
}
db_printf("inhibited\n");
return;
default:
db_printf("??? (%#x)\n", td->td_state);
return;
}
}
}
Rename 'show lockchain' to 'show locktree' and 'show threadchain' to 'show lockchain'. The churn is because I'm about to add a new 'show sleepchain' similar to 'show lockchain' for sleep locks (lockmgr and sx) and 'show threadchain' was a bit ambiguous as both commands show a chain of thread dependencies, 'lockchain' is for non-sleepable locks (mtx and rw) and 'sleepchain' is for sleepable locks.
2006-08-15 16:44:18 +00:00
DB_SHOW_COMMAND(lockchain, db_show_lockchain)
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
{
struct thread *td;
/* Figure out which thread to start with. */
if (have_addr)
ddb: finish converting boolean values. The replacement started at r283088 was necessarily incomplete without replacing boolean_t with bool. This also involved cleaning some type mismatches and ansifying old C function declarations. Pointed out by: bde Discussed with: bde, ian, jhb
2015-05-21 15:16:18 +00:00
td = db_lookup_thread(addr, true);
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
else
td = kdb_thread;
Rename 'show lockchain' to 'show locktree' and 'show threadchain' to 'show lockchain'. The churn is because I'm about to add a new 'show sleepchain' similar to 'show lockchain' for sleep locks (lockmgr and sx) and 'show threadchain' was a bit ambiguous as both commands show a chain of thread dependencies, 'lockchain' is for non-sleepable locks (mtx and rw) and 'sleepchain' is for sleepable locks.
2006-08-15 16:44:18 +00:00
print_lockchain(td, "");
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
}
Make ddb command registration dynamic so modules can extend the command set (only so long as the module is present): o add db_command_register and db_command_unregister to add and remove commands, respectively o replace linker sets with SYSINIT's (and SYSUINIT's) that register commands o expose 3 list heads: db_cmd_table, db_show_table, and db_show_all_table for registering top-level commands, show operands, and show all operands, respectively While here also: o sort command lists o add DB_ALIAS, DB_SHOW_ALIAS, and DB_SHOW_ALL_ALIAS to add aliases for existing commands o add "show all trace" as an alias for "show alltrace" o add "show all locks" as an alias for "show alllocks" Submitted by: Guillaume Ballet <gballet@gmail.com> (original version) Reviewed by: jhb MFC after: 1 month
2008-09-15 22:45:14 +00:00
DB_SHOW_ALL_COMMAND(chains, db_show_allchains)
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
{
struct thread *td;
struct proc *p;
int i;
i = 1;
Use FOREACH_PROC_IN_SYSTEM instead of using its unrolled form.
2007-01-17 14:58:53 +00:00
FOREACH_PROC_IN_SYSTEM(p) {
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
FOREACH_THREAD_IN_PROC(p, td) {
if (TD_ON_LOCK(td) && LIST_EMPTY(&td->td_contested)) {
db_printf("chain %d:\n", i++);
Rename 'show lockchain' to 'show locktree' and 'show threadchain' to 'show lockchain'. The churn is because I'm about to add a new 'show sleepchain' similar to 'show lockchain' for sleep locks (lockmgr and sx) and 'show threadchain' was a bit ambiguous as both commands show a chain of thread dependencies, 'lockchain' is for non-sleepable locks (mtx and rw) and 'sleepchain' is for sleepable locks.
2006-08-15 16:44:18 +00:00
print_lockchain(td, " ");
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
}
ddb(4): Add sleepchains to "show allchains" Reported by: markj Reviewed by: markj Sponsored by: Dell EMC Isilon Differential Revision: https://reviews.freebsd.org/D8320
2016-10-22 18:02:20 +00:00
if (TD_IS_INHIBITED(td) && TD_ON_SLEEPQ(td)) {
db_printf("chain %d:\n", i++);
print_sleepchain(td, " ");
}
Honor db_pager_quit in 'show threadchain', 'show allchains', and 'show lockchain'. This is especially helpful for the first 2 as a threadchain could get stuck in an infinite loop during a mutex deadlock.
2006-07-12 21:25:24 +00:00
if (db_pager_quit)
return;
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
}
}
}
Make ddb command registration dynamic so modules can extend the command set (only so long as the module is present): o add db_command_register and db_command_unregister to add and remove commands, respectively o replace linker sets with SYSINIT's (and SYSUINIT's) that register commands o expose 3 list heads: db_cmd_table, db_show_table, and db_show_all_table for registering top-level commands, show operands, and show all operands, respectively While here also: o sort command lists o add DB_ALIAS, DB_SHOW_ALIAS, and DB_SHOW_ALL_ALIAS to add aliases for existing commands o add "show all trace" as an alias for "show alltrace" o add "show all locks" as an alias for "show alllocks" Submitted by: Guillaume Ballet <gballet@gmail.com> (original version) Reviewed by: jhb MFC after: 1 month
2008-09-15 22:45:14 +00:00
DB_SHOW_ALIAS(allchains, db_show_allchains)
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
/*
* Show all the threads a particular thread is waiting on based on
* sleepable locks.
*/
static void
print_sleepchain(struct thread *td, const char *prefix)
{
struct thread *owner;
/*
* Follow the chain. We keep walking as long as the thread is
* blocked on a sleep lock that has an owner.
*/
while (!db_pager_quit) {
db_printf("%sthread %d (pid %d, %s) ", prefix, td->td_tid,
Finish r173600. There is no need to test a condition if both cases result in the same value. Found by: PVS-Studio Sponsored by: The FreeBSD Foundation MFC after: 1 week
2016-02-10 21:16:37 +00:00
td->td_proc->p_pid, td->td_name);
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
switch (td->td_state) {
case TDS_INACTIVE:
db_printf("is inactive\n");
return;
case TDS_CAN_RUN:
db_printf("can run\n");
return;
case TDS_RUNQ:
db_printf("is on a run queue\n");
return;
case TDS_RUNNING:
db_printf("running on CPU %d\n", td->td_oncpu);
return;
case TDS_INHIBITED:
if (TD_ON_SLEEPQ(td)) {
if (lockmgr_chain(td, &owner) ||
sx_chain(td, &owner)) {
if (owner == NULL)
return;
td = owner;
break;
}
db_printf("sleeping on %p \"%s\"\n",
td->td_wchan, td->td_wmesg);
return;
}
db_printf("inhibited\n");
return;
default:
db_printf("??? (%#x)\n", td->td_state);
return;
}
}
}
DB_SHOW_COMMAND(sleepchain, db_show_sleepchain)
{
struct thread *td;
/* Figure out which thread to start with. */
if (have_addr)
ddb: finish converting boolean values. The replacement started at r283088 was necessarily incomplete without replacing boolean_t with bool. This also involved cleaning some type mismatches and ansifying old C function declarations. Pointed out by: bde Discussed with: bde, ian, jhb
2015-05-21 15:16:18 +00:00
td = db_lookup_thread(addr, true);
Add a new 'show sleepchain' ddb command similar to 'show lockchain' except that it operates on lockmgr and sx locks. This can be useful for tracking down vnode deadlocks in VFS for example. Note that this command is a bit more fragile than 'show lockchain' as we have to poke around at the wait channel of a thread to see if it points to either a struct lock or a condition variable inside of a struct sx. If td_wchan points to something unmapped, then this command will terminate early due to a fault, but no harm will be done.
2006-08-15 18:29:01 +00:00
else
td = kdb_thread;
print_sleepchain(td, "");
}
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
static void print_waiters(struct turnstile *ts, int indent);
static void
print_waiter(struct thread *td, int indent)
{
struct turnstile *ts;
int i;
Honor db_pager_quit in 'show threadchain', 'show allchains', and 'show lockchain'. This is especially helpful for the first 2 as a threadchain could get stuck in an infinite loop during a mutex deadlock.
2006-07-12 21:25:24 +00:00
if (db_pager_quit)
return;
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
for (i = 0; i < indent; i++)
db_printf(" ");
print_thread(td, "thread ");
LIST_FOREACH(ts, &td->td_contested, ts_link)
print_waiters(ts, indent + 1);
}
static void
print_waiters(struct turnstile *ts, int indent)
{
struct lock_object *lock;
struct lock_class *class;
struct thread *td;
int i;
Honor db_pager_quit in 'show threadchain', 'show allchains', and 'show lockchain'. This is especially helpful for the first 2 as a threadchain could get stuck in an infinite loop during a mutex deadlock.
2006-07-12 21:25:24 +00:00
if (db_pager_quit)
return;
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
lock = ts->ts_lockobj;
class = LOCK_CLASS(lock);
for (i = 0; i < indent; i++)
db_printf(" ");
db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name, lock->lo_name);
TAILQ_FOREACH(td, &ts->ts_blocked[TS_EXCLUSIVE_QUEUE], td_lockq)
print_waiter(td, indent + 1);
TAILQ_FOREACH(td, &ts->ts_blocked[TS_SHARED_QUEUE], td_lockq)
print_waiter(td, indent + 1);
TAILQ_FOREACH(td, &ts->ts_pending, td_lockq)
print_waiter(td, indent + 1);
}
Rename 'show lockchain' to 'show locktree' and 'show threadchain' to 'show lockchain'. The churn is because I'm about to add a new 'show sleepchain' similar to 'show lockchain' for sleep locks (lockmgr and sx) and 'show threadchain' was a bit ambiguous as both commands show a chain of thread dependencies, 'lockchain' is for non-sleepable locks (mtx and rw) and 'sleepchain' is for sleepable locks.
2006-08-15 16:44:18 +00:00
DB_SHOW_COMMAND(locktree, db_show_locktree)
Add some new commands to hopefully make it easier to diagnose lock-related problems in ddb: - "show threadchain [thread]" will start with the specified thread (or the current kdb thread by default) and show it's state. If it is blocked on a lock, it will find the owner of the lock and show its state, etc. - "show allchains" will find all of the threads that are blocked on a lock (but do not have any threads blocked on a lock they hold) and show the resulting thread chain. - "show lockchain <lock>" takes a pointer to a lock_object (such as a mutex or rwlock). If there is a turnstile for that lock, then it will display all the threads blocked on the lock. In addition, for each thread blocked on the lock, it will display any contested locks they hold, and recurse on those locks to show any threads blocked on those locks, etc.
2006-04-25 20:28:17 +00:00
{
struct lock_object *lock;
struct lock_class *class;
struct turnstile_chain *tc;
struct turnstile *ts;
if (!have_addr)
return;
lock = (struct lock_object *)addr;
tc = TC_LOOKUP(lock);
LIST_FOREACH(ts, &tc->tc_turnstiles, ts_hash)
if (ts->ts_lockobj == lock)
break;
if (ts == NULL) {
class = LOCK_CLASS(lock);
db_printf("lock %p (%s) \"%s\"\n", lock, class->lc_name,
lock->lo_name);
} else
print_waiters(ts, 0);
}
- Add support for having both a shared and exclusive queue of threads in each turnstile. Also, allow for the owner thread pointer of a turnstile to be NULL. This is needed for the upcoming reader/writer lock implementation. - Add a new ddb command 'show turnstile' that will look up the turnstile associated with the given lock argument and display useful information like the list of threads blocked on each queue, etc. If there isn't an active turnstile for a lock at the specified address, then the function will see if there is an active turnstile at the specified address and display info about it if so. - Adjust the mutex code to handle the turnstile API changes. Tested on: i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
#endif
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