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freebsd-skq/sys/kern/kern_mutex.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
/*
Remove definition of witness and comment stating that this file implements witness. Witness moved off to subr_witness.c a while ago.
2001-11-15 19:08:55 +00:00
* Machine independent bits of mutex implementation.
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 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
#include "opt_adaptive_mutexes.h"
Include the right headers to get the DDB #define and the db_active variable.
2000-11-15 22:08:16 +00:00
#include "opt_ddb.h"
add options MPROF_BUFFERS and MPROF_HASH_SIZE that adjust the sizes of the mutex profiling buffers. Document them in the man page and in NOTES. Ensure _HASH_SIZE is larger than _BUFFERS with a cpp error.
2004-08-19 06:38:26 +00:00
#include "opt_mprof.h"
Add a new kernel option MUTEX_WAKE_ALL that changes the mutex unlock code to awaken all waiters when a contested mutex is released instead of just the highest priority waiter. If the various threads are awakened in sequence then each thread may acquire and release the lock in question without contention resulting in fewer expensive unlock and lock operations. This old behavior of waking just the highest priority is still used if this option is specified. Making the algorithm conditional on a kernel option will allows us to benchmark both cases later and determine which one should be used by default. Requested by: tanimura-san
2004-04-06 19:12:24 +00:00
#include "opt_mutex_wake_all.h"
Turn PREEMPTION into a kernel option. Make sure that it's defined if FULL_PREEMPTION is defined. Add a runtime warning to ULE if PREEMPTION is enabled (code inspired by the PREEMPTION warning in kern_switch.c). This is a possible MT5 candidate.
2004-09-02 18:59:15 +00:00
#include "opt_sched.h"
- Use MUTEX_DECLARE() and MTX_COLD for the WITNESS code's internal mutex so it can function before malloc(9) is up and running. - Add two new options WITNESS_DDB and WITNESS_SKIPSPIN. If WITNESS_SKIPSPIN is enabled, then spin mutexes are ignored by the WITNESS code. If WITNESS_DDB is turned on and DDB is compiled into the kernel, then the kernel will drop into DDB when either a lock hierarchy violation occurs or mutexes are held when going to sleep. - Add some new sysctls: debug.witness_ddb is a read-write sysctl that corresponds to WITNESS_DDB. The kernel option merely changes the default value to on at boot. debug.witness_skipspin is a read-only sysctl that one can use to determine if the kernel was compiled with WITNESS_SKIPSPIN. - Wipe out the BSD/OS-specific lock order lists. We get to build our own lists now as we add mutexes to the kernel.
2000-10-27 02:59:30 +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>
- 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/bus.h>
Ignore mutex asserts when we're dumping as well. This allows me to panic a system from DDB when INVARIANTS is compiled into the kernel on a scsi system.
2005-07-30 05:54:30 +00:00
#include <sys/conf.h>
Update for the KDB framework: o Make debugging code conditional upon KDB instead of DDB. o Call kdb_enter() instead of Debugger(). o Call kdb_backtrace() instead of db_print_backtrace() or backtrace(). kern_mutex.c: o Replace checks for db_active with checks for kdb_active and make them unconditional. kern_shutdown.c: o s/DDB_UNATTENDED/KDB_UNATTENDED/g o s/DDB_TRACE/KDB_TRACE/g o Save the TID of the thread doing the kernel dump so the debugger knows which thread to select as the current when debugging the kernel core file. o Clear kdb_active instead of db_active and do so unconditionally. o Remove backtrace() implementation. kern_synch.c: o Call kdb_reenter() instead of db_error().
2004-07-10 21:36:01 +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>
Undo part of the tangle of having sys/lock.h and sys/mutex.h included in other "system" header files. Also help the deprecation of lockmgr.h by making it a sub-include of sys/lock.h and removing sys/lockmgr.h form kernel .c files. Sort sys/*.h includes where possible in affected files. OK'ed by: bde (with reservations)
2001-05-01 08:13:21 +00:00
#include <sys/malloc.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/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>
Count the context switch when blocking on a mutex as a voluntary context switch. Count the context switch when preempting the current thread to let a higher priority thread blocked on a mutex we just released run as an involuntary context switch. Reported by: bde
2001-06-25 18:29:32 +00:00
#include <sys/resourcevar.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>
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/sbuf.h>
- Use MUTEX_DECLARE() and MTX_COLD for the WITNESS code's internal mutex so it can function before malloc(9) is up and running. - Add two new options WITNESS_DDB and WITNESS_SKIPSPIN. If WITNESS_SKIPSPIN is enabled, then spin mutexes are ignored by the WITNESS code. If WITNESS_DDB is turned on and DDB is compiled into the kernel, then the kernel will drop into DDB when either a lock hierarchy violation occurs or mutexes are held when going to sleep. - Add some new sysctls: debug.witness_ddb is a read-write sysctl that corresponds to WITNESS_DDB. The kernel option merely changes the default value to on at boot. debug.witness_skipspin is a read-only sysctl that one can use to determine if the kernel was compiled with WITNESS_SKIPSPIN. - Wipe out the BSD/OS-specific lock order lists. We get to build our own lists now as we add mutexes to the kernel.
2000-10-27 02:59:30 +00:00
#include <sys/sysctl.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/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
#include <sys/vmmeter.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
- 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 <machine/atomic.h>
#include <machine/bus.h>
#include <machine/clock.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 <machine/cpu.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 the right headers to get the DDB #define and the db_active variable.
2000-11-15 22:08:16 +00:00
#include <ddb/ddb.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 <vm/vm.h>
#include <vm/vm_extern.h>
Force MUTEX_WAKE_ALL. A race condition in single thread wakeup may break priority inheritance. Tested by: pho Reviewed by: jhb,julian Approved by: sam (mentor) MFC: ASAP
2004-10-12 16:28:18 +00:00
/*
* Force MUTEX_WAKE_ALL for now.
* single thread wakeup needs fixes to avoid race conditions with
* priority inheritance.
*/
#ifndef MUTEX_WAKE_ALL
#define MUTEX_WAKE_ALL
#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
/*
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
* Internal utility macros.
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
#define mtx_unowned(m) ((m)->mtx_lock == MTX_UNOWNED)
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
#define mtx_owner(m) (mtx_unowned((m)) ? 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
: (struct thread *)((m)->mtx_lock & MTX_FLAGMASK))
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
/*
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
* Lock classes for sleep and spin mutexes.
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 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
struct lock_class lock_class_mtx_sleep = {
"sleep mutex",
LC_SLEEPLOCK | LC_RECURSABLE
};
struct lock_class lock_class_mtx_spin = {
"spin mutex",
LC_SPINLOCK | LC_RECURSABLE
};
- 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
- 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
/*
* System-wide mutexes
*/
struct mtx sched_lock;
struct mtx Giant;
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
#ifdef MUTEX_PROFILING
SYSCTL_NODE(_debug, OID_AUTO, mutex, CTLFLAG_RD, NULL, "mutex debugging");
SYSCTL_NODE(_debug_mutex, OID_AUTO, prof, CTLFLAG_RD, NULL, "mutex profiling");
static int mutex_prof_enable = 0;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, enable, CTLFLAG_RW,
&mutex_prof_enable, 0, "Enable tracing of mutex holdtime");
struct mutex_prof {
Reduce the overhead of the mutex statistics gathering code, try to produce shorter lines in the report, and clean up some minor style issues.
2002-10-21 18:48:28 +00:00
const char *name;
const char *file;
int line;
There's absolutely no need for a struct-within-a-struct, so move the counters out of the inner struct and remove it.
2003-01-21 20:33:27 +00:00
uintmax_t cnt_max;
uintmax_t cnt_tot;
uintmax_t cnt_cur;
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
uintmax_t cnt_contest_holding;
uintmax_t cnt_contest_locking;
Revert to open hashing. It makes the code simpler, and works farily well even when the number of records approaches the size of the hash table. Besides, the previous implementation (using linear probing) was broken :) Also, use the newly introduced MTX_SYSINIT.
2002-04-02 23:26:32 +00:00
struct mutex_prof *next;
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
};
/*
* mprof_buf is a static pool of profiling records to avoid possible
* reentrance of the memory allocation functions.
*
* Note: NUM_MPROF_BUFFERS must be smaller than MPROF_HASH_SIZE.
*/
add options MPROF_BUFFERS and MPROF_HASH_SIZE that adjust the sizes of the mutex profiling buffers. Document them in the man page and in NOTES. Ensure _HASH_SIZE is larger than _BUFFERS with a cpp error.
2004-08-19 06:38:26 +00:00
#ifdef MPROF_BUFFERS
#define NUM_MPROF_BUFFERS MPROF_BUFFERS
#else
Reduce the overhead of the mutex statistics gathering code, try to produce shorter lines in the report, and clean up some minor style issues.
2002-10-21 18:48:28 +00:00
#define NUM_MPROF_BUFFERS 1000
add options MPROF_BUFFERS and MPROF_HASH_SIZE that adjust the sizes of the mutex profiling buffers. Document them in the man page and in NOTES. Ensure _HASH_SIZE is larger than _BUFFERS with a cpp error.
2004-08-19 06:38:26 +00:00
#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
static struct mutex_prof mprof_buf[NUM_MPROF_BUFFERS];
static int first_free_mprof_buf;
add options MPROF_BUFFERS and MPROF_HASH_SIZE that adjust the sizes of the mutex profiling buffers. Document them in the man page and in NOTES. Ensure _HASH_SIZE is larger than _BUFFERS with a cpp error.
2004-08-19 06:38:26 +00:00
#ifndef MPROF_HASH_SIZE
Reduce the overhead of the mutex statistics gathering code, try to produce shorter lines in the report, and clean up some minor style issues.
2002-10-21 18:48:28 +00:00
#define MPROF_HASH_SIZE 1009
add options MPROF_BUFFERS and MPROF_HASH_SIZE that adjust the sizes of the mutex profiling buffers. Document them in the man page and in NOTES. Ensure _HASH_SIZE is larger than _BUFFERS with a cpp error.
2004-08-19 06:38:26 +00:00
#endif
#if NUM_MPROF_BUFFERS >= MPROF_HASH_SIZE
#error MPROF_BUFFERS must be larger than MPROF_HASH_SIZE
#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
static struct mutex_prof *mprof_hash[MPROF_HASH_SIZE];
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
/* SWAG: sbuf size = avg stat. line size * number of locks */
#define MPROF_SBUF_SIZE 256 * 400
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
static int mutex_prof_acquisitions;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, acquisitions, CTLFLAG_RD,
&mutex_prof_acquisitions, 0, "Number of mutex acquistions recorded");
static int mutex_prof_records;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, records, CTLFLAG_RD,
&mutex_prof_records, 0, "Number of profiling records");
static int mutex_prof_maxrecords = NUM_MPROF_BUFFERS;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, maxrecords, CTLFLAG_RD,
&mutex_prof_maxrecords, 0, "Maximum number of profiling records");
static int mutex_prof_rejected;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, rejected, CTLFLAG_RD,
&mutex_prof_rejected, 0, "Number of rejected profiling records");
static int mutex_prof_hashsize = MPROF_HASH_SIZE;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, hashsize, CTLFLAG_RD,
&mutex_prof_hashsize, 0, "Hash size");
static int mutex_prof_collisions = 0;
SYSCTL_INT(_debug_mutex_prof, OID_AUTO, collisions, CTLFLAG_RD,
&mutex_prof_collisions, 0, "Number of hash collisions");
/*
* mprof_mtx protects the profiling buffers and the hash.
*/
static struct mtx mprof_mtx;
Revert to open hashing. It makes the code simpler, and works farily well even when the number of records approaches the size of the hash table. Besides, the previous implementation (using linear probing) was broken :) Also, use the newly introduced MTX_SYSINIT.
2002-04-02 23:26:32 +00:00
MTX_SYSINIT(mprof, &mprof_mtx, "mutex profiling lock", MTX_SPIN | MTX_QUIET);
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
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
static u_int64_t
nanoseconds(void)
{
struct timespec tv;
nanotime(&tv);
return (tv.tv_sec * (u_int64_t)1000000000 + tv.tv_nsec);
}
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
static int
dump_mutex_prof_stats(SYSCTL_HANDLER_ARGS)
{
struct sbuf *sb;
int error, i;
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
static int multiplier = 1;
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
if (first_free_mprof_buf == 0)
Reduce the overhead of the mutex statistics gathering code, try to produce shorter lines in the report, and clean up some minor style issues.
2002-10-21 18:48:28 +00:00
return (SYSCTL_OUT(req, "No locking recorded",
sizeof("No locking recorded")));
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
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
retry_sbufops:
sb = sbuf_new(NULL, NULL, MPROF_SBUF_SIZE * multiplier, SBUF_FIXEDLEN);
Add additional newline to debug.mutex.prof.stats header, so that column names are printed exactly above the columns.
2005-04-08 14:14:09 +00:00
sbuf_printf(sb, "\n%6s %12s %11s %5s %12s %12s %s\n",
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
"max", "total", "count", "avg", "cnt_hold", "cnt_lock", "name");
Reduce the overhead of the mutex statistics gathering code, try to produce shorter lines in the report, and clean up some minor style issues.
2002-10-21 18:48:28 +00:00
/*
* XXX this spinlock seems to be by far the largest perpetrator
* of spinlock latency (1.6 msec on an Athlon1600 was recorded
* even before I pessimized it further by moving the average
* computation here).
*/
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
mtx_lock_spin(&mprof_mtx);
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
for (i = 0; i < first_free_mprof_buf; ++i) {
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
sbuf_printf(sb, "%6ju %12ju %11ju %5ju %12ju %12ju %s:%d (%s)\n",
There's absolutely no need for a struct-within-a-struct, so move the counters out of the inner struct and remove it.
2003-01-21 20:33:27 +00:00
mprof_buf[i].cnt_max / 1000,
mprof_buf[i].cnt_tot / 1000,
mprof_buf[i].cnt_cur,
mprof_buf[i].cnt_cur == 0 ? (uintmax_t)0 :
mprof_buf[i].cnt_tot / (mprof_buf[i].cnt_cur * 1000),
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
mprof_buf[i].cnt_contest_holding,
mprof_buf[i].cnt_contest_locking,
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
mprof_buf[i].file, mprof_buf[i].line, mprof_buf[i].name);
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
if (sbuf_overflowed(sb)) {
mtx_unlock_spin(&mprof_mtx);
sbuf_delete(sb);
multiplier++;
goto retry_sbufops;
}
}
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
mtx_unlock_spin(&mprof_mtx);
sbuf_finish(sb);
error = SYSCTL_OUT(req, sbuf_data(sb), sbuf_len(sb) + 1);
sbuf_delete(sb);
return (error);
}
Reduce the overhead of the mutex statistics gathering code, try to produce shorter lines in the report, and clean up some minor style issues.
2002-10-21 18:48:28 +00:00
SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, stats, CTLTYPE_STRING | CTLFLAG_RD,
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
NULL, 0, dump_mutex_prof_stats, "A", "Mutex profiling statistics");
Add a reset sysctl for mutex profiling: zeros all of the mutex profiling buffers and hash table. This makes it a lot easier to do multiple profiling runs without rebooting or performing gratuitous arithmetic. Sysctl is named debug.mutex.prof.reset. Reviewed by: jake
2004-01-28 22:11:53 +00:00
static int
reset_mutex_prof_stats(SYSCTL_HANDLER_ARGS)
{
int error, v;
if (first_free_mprof_buf == 0)
return (0);
v = 0;
error = sysctl_handle_int(oidp, &v, 0, req);
if (error)
return (error);
if (req->newptr == NULL)
return (error);
if (v == 0)
return (0);
mtx_lock_spin(&mprof_mtx);
bzero(mprof_buf, sizeof(*mprof_buf) * first_free_mprof_buf);
bzero(mprof_hash, sizeof(struct mtx *) * MPROF_HASH_SIZE);
first_free_mprof_buf = 0;
mtx_unlock_spin(&mprof_mtx);
return (0);
}
SYSCTL_PROC(_debug_mutex_prof, OID_AUTO, reset, CTLTYPE_INT | CTLFLAG_RW,
NULL, 0, reset_mutex_prof_stats, "I", "Reset mutex profiling statistics");
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
#endif
- 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
/*
* Function versions of the inlined __mtx_* macros. These are used by
* modules and can also be called from assembly language if needed.
*/
void
_mtx_lock_flags(struct mtx *m, int opts, const char *file, int line)
{
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
MPASS(curthread != NULL);
Add some KASSERT()'s to ensure that we don't perform spin mutex ops on sleep mutexes and vice versa. WITNESS normally should catch this but not everyone uses WITNESS so this is a fallback to catch nasty but easy to do bugs.
2002-09-03 18:25:16 +00:00
KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
("mtx_lock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
file, line));
Rework witness_lock() to make it slightly more useful and flexible. - witness_lock() is split into two pieces: witness_checkorder() and witness_lock(). Witness_checkorder() determines if acquiring a specified lock at the time it is called would result in a lock order. It optionally adds a new lock order relationship as well. witness_lock() updates witness's data structures to assume that a lock has been acquired by stick a new lock instance in the appropriate lock instance list. - The mutex and sx lock functions now call checkorder() prior to trying to acquire a lock and continue to call witness_lock() after the acquire is completed. This will let witness catch a deadlock before it happens rather than trying to do so after the threads have deadlocked (i.e. never actually report it). - A new function witness_defineorder() has been added that adds a lock order between two locks at runtime without having to acquire the locks. If the lock order cannot be added it will return an error. This function is available to programmers via the WITNESS_DEFINEORDER() macro which accepts either two mutexes or two sx locks as its arguments. - A few simple wrapper macros were added to allow developers to call witness_checkorder() anywhere as a way of enforcing locking assertions in code that might acquire a certain lock in some situations. The macros are: witness_check_{mutex,shared_sx,exclusive_sx} and take an appropriate lock as the sole argument. - The code to remove a lock instance from a lock list in witness_unlock() was unnested by using a goto to vastly improve the readability of this function.
2004-01-28 20:39:57 +00:00
WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line);
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
_get_sleep_lock(m, curthread, opts, file, line);
LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
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
#ifdef MUTEX_PROFILING
/* don't reset the timer when/if recursing */
Add mtx_ prefixes to the fields used for mutex profiling, and fix a bug where the profiling code would report the release point instead of the acquisition point. Requested by: bde
2002-07-03 01:50:27 +00:00
if (m->mtx_acqtime == 0) {
m->mtx_filename = file;
m->mtx_lineno = line;
m->mtx_acqtime = mutex_prof_enable ? nanoseconds() : 0;
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
++mutex_prof_acquisitions;
}
#endif
- 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
_mtx_unlock_flags(struct mtx *m, int opts, const char *file, int line)
{
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
MPASS(curthread != NULL);
Add some KASSERT()'s to ensure that we don't perform spin mutex ops on sleep mutexes and vice versa. WITNESS normally should catch this but not everyone uses WITNESS so this is a fallback to catch nasty but easy to do bugs.
2002-09-03 18:25:16 +00:00
KASSERT(m->mtx_object.lo_class == &lock_class_mtx_sleep,
("mtx_unlock() of spin mutex %s @ %s:%d", m->mtx_object.lo_name,
file, line));
Whitespace cleanup.
2002-10-23 10:26:54 +00:00
WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
Add some KASSERT()'s to ensure that we don't perform spin mutex ops on sleep mutexes and vice versa. WITNESS normally should catch this but not everyone uses WITNESS so this is a fallback to catch nasty but easy to do bugs.
2002-09-03 18:25:16 +00:00
LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
Remove superflous parens after de-macroizing.
2001-09-26 00:05:18 +00:00
mtx_assert(m, MA_OWNED);
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
#ifdef MUTEX_PROFILING
Add mtx_ prefixes to the fields used for mutex profiling, and fix a bug where the profiling code would report the release point instead of the acquisition point. Requested by: bde
2002-07-03 01:50:27 +00:00
if (m->mtx_acqtime != 0) {
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
static const char *unknown = "(unknown)";
struct mutex_prof *mpp;
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
u_int64_t acqtime, now;
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
const char *p, *q;
Revert to open hashing. It makes the code simpler, and works farily well even when the number of records approaches the size of the hash table. Besides, the previous implementation (using linear probing) was broken :) Also, use the newly introduced MTX_SYSINIT.
2002-04-02 23:26:32 +00:00
volatile u_int hash;
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
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
now = nanoseconds();
Add mtx_ prefixes to the fields used for mutex profiling, and fix a bug where the profiling code would report the release point instead of the acquisition point. Requested by: bde
2002-07-03 01:50:27 +00:00
acqtime = m->mtx_acqtime;
m->mtx_acqtime = 0;
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
if (now <= acqtime)
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
goto out;
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
for (p = m->mtx_filename;
p != NULL && strncmp(p, "../", 3) == 0; p += 3)
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
/* nothing */ ;
if (p == NULL || *p == '\0')
p = unknown;
Add mtx_ prefixes to the fields used for mutex profiling, and fix a bug where the profiling code would report the release point instead of the acquisition point. Requested by: bde
2002-07-03 01:50:27 +00:00
for (hash = m->mtx_lineno, q = p; *q != '\0'; ++q)
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
hash = (hash * 2 + *q) % MPROF_HASH_SIZE;
mtx_lock_spin(&mprof_mtx);
Revert to open hashing. It makes the code simpler, and works farily well even when the number of records approaches the size of the hash table. Besides, the previous implementation (using linear probing) was broken :) Also, use the newly introduced MTX_SYSINIT.
2002-04-02 23:26:32 +00:00
for (mpp = mprof_hash[hash]; mpp != NULL; mpp = mpp->next)
Add mtx_ prefixes to the fields used for mutex profiling, and fix a bug where the profiling code would report the release point instead of the acquisition point. Requested by: bde
2002-07-03 01:50:27 +00:00
if (mpp->line == m->mtx_lineno &&
strcmp(mpp->file, p) == 0)
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
break;
if (mpp == NULL) {
/* Just exit if we cannot get a trace buffer */
if (first_free_mprof_buf >= NUM_MPROF_BUFFERS) {
++mutex_prof_rejected;
goto unlock;
}
mpp = &mprof_buf[first_free_mprof_buf++];
mpp->name = mtx_name(m);
mpp->file = p;
Add mtx_ prefixes to the fields used for mutex profiling, and fix a bug where the profiling code would report the release point instead of the acquisition point. Requested by: bde
2002-07-03 01:50:27 +00:00
mpp->line = m->mtx_lineno;
Revert to open hashing. It makes the code simpler, and works farily well even when the number of records approaches the size of the hash table. Besides, the previous implementation (using linear probing) was broken :) Also, use the newly introduced MTX_SYSINIT.
2002-04-02 23:26:32 +00:00
mpp->next = mprof_hash[hash];
if (mprof_hash[hash] != NULL)
++mutex_prof_collisions;
Whitespace cleanup.
2002-10-23 10:26:54 +00:00
mprof_hash[hash] = mpp;
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
++mutex_prof_records;
}
/*
* Record if the mutex has been held longer now than ever
Reduce the overhead of the mutex statistics gathering code, try to produce shorter lines in the report, and clean up some minor style issues.
2002-10-21 18:48:28 +00:00
* before.
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
*/
There's absolutely no need for a struct-within-a-struct, so move the counters out of the inner struct and remove it.
2003-01-21 20:33:27 +00:00
if (now - acqtime > mpp->cnt_max)
mpp->cnt_max = now - acqtime;
mpp->cnt_tot += now - acqtime;
mpp->cnt_cur++;
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
/*
* There's a small race, really we should cmpxchg
* 0 with the current value, but that would bill
* the contention to the wrong lock instance if
* it followed this also.
*/
mpp->cnt_contest_holding += m->mtx_contest_holding;
m->mtx_contest_holding = 0;
mpp->cnt_contest_locking += m->mtx_contest_locking;
m->mtx_contest_locking = 0;
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
unlock:
mtx_unlock_spin(&mprof_mtx);
}
out:
#endif
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
_rel_sleep_lock(m, curthread, opts, file, line);
- 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
_mtx_lock_spin_flags(struct mtx *m, int opts, const char *file, int line)
{
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
MPASS(curthread != NULL);
Add some KASSERT()'s to ensure that we don't perform spin mutex ops on sleep mutexes and vice versa. WITNESS normally should catch this but not everyone uses WITNESS so this is a fallback to catch nasty but easy to do bugs.
2002-09-03 18:25:16 +00:00
KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
("mtx_lock_spin() of sleep mutex %s @ %s:%d",
m->mtx_object.lo_name, file, line));
Rework witness_lock() to make it slightly more useful and flexible. - witness_lock() is split into two pieces: witness_checkorder() and witness_lock(). Witness_checkorder() determines if acquiring a specified lock at the time it is called would result in a lock order. It optionally adds a new lock order relationship as well. witness_lock() updates witness's data structures to assume that a lock has been acquired by stick a new lock instance in the appropriate lock instance list. - The mutex and sx lock functions now call checkorder() prior to trying to acquire a lock and continue to call witness_lock() after the acquire is completed. This will let witness catch a deadlock before it happens rather than trying to do so after the threads have deadlocked (i.e. never actually report it). - A new function witness_defineorder() has been added that adds a lock order between two locks at runtime without having to acquire the locks. If the lock order cannot be added it will return an error. This function is available to programmers via the WITNESS_DEFINEORDER() macro which accepts either two mutexes or two sx locks as its arguments. - A few simple wrapper macros were added to allow developers to call witness_checkorder() anywhere as a way of enforcing locking assertions in code that might acquire a certain lock in some situations. The macros are: witness_check_{mutex,shared_sx,exclusive_sx} and take an appropriate lock as the sole argument. - The code to remove a lock instance from a lock list in witness_unlock() was unnested by using a goto to vastly improve the readability of this function.
2004-01-28 20:39:57 +00:00
WITNESS_CHECKORDER(&m->mtx_object, opts | LOP_NEWORDER | LOP_EXCLUSIVE,
file, line);
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
_get_spin_lock(m, curthread, opts, file, line);
LOCK_LOG_LOCK("LOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
- 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
_mtx_unlock_spin_flags(struct mtx *m, int opts, const char *file, int line)
{
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
MPASS(curthread != NULL);
Add some KASSERT()'s to ensure that we don't perform spin mutex ops on sleep mutexes and vice versa. WITNESS normally should catch this but not everyone uses WITNESS so this is a fallback to catch nasty but easy to do bugs.
2002-09-03 18:25:16 +00:00
KASSERT(m->mtx_object.lo_class == &lock_class_mtx_spin,
("mtx_unlock_spin() of sleep mutex %s @ %s:%d",
m->mtx_object.lo_name, file, line));
Whitespace cleanup.
2002-10-23 10:26:54 +00:00
WITNESS_UNLOCK(&m->mtx_object, opts | LOP_EXCLUSIVE, file, line);
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
LOCK_LOG_LOCK("UNLOCK", &m->mtx_object, opts, m->mtx_recurse, file,
line);
Add some KASSERT()'s to ensure that we don't perform spin mutex ops on sleep mutexes and vice versa. WITNESS normally should catch this but not everyone uses WITNESS so this is a fallback to catch nasty but easy to do bugs.
2002-09-03 18:25:16 +00:00
mtx_assert(m, MA_OWNED);
Since we no longer inline any debugging code in the mutex operations, move all the debugging code into the function versions of the mutex operations in kern_mutex.c. This reduced the __mtx_* macros to simply wrappers of the _{get,rel}_lock_* macros, so the __mtx_* macros were also abolished in favor of just calling the _{get,rel}_lock_* macros. The tangled hairy mass of macros calling macros is at least a bit more sane now.
2001-09-22 21:19:55 +00:00
_rel_spin_lock(m);
- 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
}
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
* The important part of mtx_trylock{,_flags}()
- Allow mtx_trylock() to recurse on a recursive mutex. Attempts to recurse on a non-recursive mutex will fail but will not trigger any assertions. - Add an assertion to mtx_lock() that one never recurses on a non-recursive mutex. This is mostly useful for the non-WITNESS case. Requested by: deischen, julian, others (1)
2004-01-05 23:09:51 +00:00
* Tries to acquire lock `m.' If this function is called on a mutex that
* is already owned, it will recursively acquire the 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
*/
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
int
_mtx_trylock(struct mtx *m, int opts, const char *file, int line)
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
int rval;
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
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(curthread != 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
- Allow mtx_trylock() to recurse on a recursive mutex. Attempts to recurse on a non-recursive mutex will fail but will not trigger any assertions. - Add an assertion to mtx_lock() that one never recurses on a non-recursive mutex. This is mostly useful for the non-WITNESS case. Requested by: deischen, julian, others (1)
2004-01-05 23:09:51 +00:00
if (mtx_owned(m) && (m->mtx_object.lo_flags & LO_RECURSABLE) != 0) {
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
rval = 1;
} else
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
rval = _obtain_lock(m, (uintptr_t)curthread);
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
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
LOCK_LOG_TRY("LOCK", &m->mtx_object, opts, rval, file, line);
Properly assert that mtx_trylock() is not called on a mutex we already owned. Previously the KASSERT would only trigger if we successfully acquired a lock that we already held. However, _obtain_lock() fails to acquire locks that we already hold, so the KASSERT was never checked in the case it was supposed to fail.
2003-03-04 20:30:30 +00:00
if (rval)
- Move state about lock objects out of struct lock_object and into a new struct lock_instance that is stored in the per-process and per-CPU lock lists. Previously, the lock lists just kept a pointer to each lock held. That pointer is now replaced by a lock instance which contains a pointer to the lock object, the file and line of the last acquisition of a lock, and various flags about a lock including its recursion count. - If we sleep while holding a sleepable lock, then mark that lock instance as having slept and ignore any lock order violations that occur while acquiring Giant when we wake up with slept locks. This is ok because of Giant's special nature. - Allow witness to differentiate between shared and exclusive locks and unlocks of a lock. Witness will now detect the case when a lock is acquired first in one mode and then in another. Mutexes are always locked and unlocked exclusively. Witness will also now detect the case where a process attempts to unlock a shared lock while holding an exclusive lock and vice versa. - Fix a bug in the lock list implementation where we used the wrong constant to detect the case where a lock list entry was full.
2001-05-04 17:15:16 +00:00
WITNESS_LOCK(&m->mtx_object, opts | LOP_EXCLUSIVE | LOP_TRYLOCK,
file, line);
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
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
return (rval);
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
* _mtx_lock_sleep: the tougher part of acquiring an MTX_DEF lock.
*
* We call this if the lock is either contested (i.e. we need to go to
* sleep waiting for it), or if we need to recurse on it.
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
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
_mtx_lock_sleep(struct mtx *m, uintptr_t tid, int opts, const char *file,
Cache the value of curthread in the _get_sleep_lock() and _get_spin_lock() macros and pass the value to the associated _mtx_*() functions to avoid more curthread dereferences in the function implementations. This provided a very modest perf improvement in some benchmarks. Suggested by: rwatson Tested by: scottl
2004-08-04 20:18:45 +00:00
int line)
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
{
Enable ADAPTIVE_MUTEXES by default by changing the sense of the option to NO_ADAPTIVE_MUTEXES. This option has been enabled by default on amd64 for quite some time, and has been extensively tested on i386 and sparc64. It shows measurable performance gains in many circumstances, and few negative effects. It would be nice in t he future if adaptive mutexes actually went to sleep after a certain amount of spinning, but that will require quite a bit more testing.
2004-07-18 15:59:03 +00:00
#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
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
struct thread *owner;
#endif
Miscellaneous cleanups to _mtx_lock_sleep(): - Declare some local variables at the top of the function instead of in a nested block. - Use mtx_owned() instead of masking off bits from mtx_lock manually. - Read the value of mtx_lock into 'v' as a separate line rather than inside an if statement for clarity. This code is hairy enough as it is.
2003-03-04 20:32:41 +00:00
uintptr_t v;
Add a new KTR type KTR_CONTENTION, and use it in the mutex code to log the start and end of periods during which mtx_lock() is waiting to acquire a sleep mutex. The log message includes the file and line of both the waiter and the holder. Reviewed by: jhb, jake
2002-08-26 18:39:38 +00:00
#ifdef KTR
int cont_logged = 0;
#endif
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
#ifdef MUTEX_PROFILING
int contested;
#endif
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
Miscellaneous cleanups to _mtx_lock_sleep(): - Declare some local variables at the top of the function instead of in a nested block. - Use mtx_owned() instead of masking off bits from mtx_lock manually. - Read the value of mtx_lock into 'v' as a separate line rather than inside an if statement for clarity. This code is hairy enough as it is.
2003-03-04 20:32:41 +00:00
if (mtx_owned(m)) {
- Allow mtx_trylock() to recurse on a recursive mutex. Attempts to recurse on a non-recursive mutex will fail but will not trigger any assertions. - Add an assertion to mtx_lock() that one never recurses on a non-recursive mutex. This is mostly useful for the non-WITNESS case. Requested by: deischen, julian, others (1)
2004-01-05 23:09:51 +00:00
KASSERT((m->mtx_object.lo_flags & LO_RECURSABLE) != 0,
("_mtx_lock_sleep: recursed on non-recursive mutex %s @ %s:%d\n",
m->mtx_object.lo_name, file, line));
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
m->mtx_recurse++;
atomic_set_ptr(&m->mtx_lock, MTX_RECURSED);
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
- 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
CTR1(KTR_LOCK, "_mtx_lock_sleep: %p recursing", m);
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
return;
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
}
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
- Axe RETIP() as it was very i386 specific and unwieldy. Instead, use the passed in filename and line number in the KTR tracepoint message. - Even though it is #if 0'd code, change the code to detect that a process is an interrupt thread to check p->p_ithd against NULL rather than checking non-existant process flags from BSD/OS. - Use '%p' to print pointers in KTR log messages instead of assuming sizeof(int) == sizeof(void *). - Don't set p_mtxname to NULL when releasing a mutex. It doesn't hurt to leave it set (we don't clear w_mesg for example) and at least at one time in the past, there used to be race conditions in the kernel that would result in setting this to NULL causing the kernel to dereference NULL. - Make the _mtx_assert() function be compiled in if INVARIANTS_SUPPORT is defined rather than if INVARIANTS is defined so that a KLD compiled with INVARIANTS that uses mtx_assert() can be used with a kernel that just has INVARIANT_SUPPORT compiled in.
2001-02-24 19:36:13 +00:00
CTR4(KTR_LOCK,
"_mtx_lock_sleep: %s contested (lock=%p) at %s:%d",
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
m->mtx_object.lo_name, (void *)m->mtx_lock, file, line);
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 some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
#ifdef MUTEX_PROFILING
contested = 0;
#endif
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
while (!_obtain_lock(m, tid)) {
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
#ifdef MUTEX_PROFILING
contested = 1;
atomic_add_int(&m->mtx_contest_holding, 1);
#endif
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_lock(&m->mtx_object);
Miscellaneous cleanups to _mtx_lock_sleep(): - Declare some local variables at the top of the function instead of in a nested block. - Use mtx_owned() instead of masking off bits from mtx_lock manually. - Read the value of mtx_lock into 'v' as a separate line rather than inside an if statement for clarity. This code is hairy enough as it is.
2003-03-04 20:32:41 +00:00
v = m->mtx_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
/*
* Check if the lock has been released while spinning 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
* the turnstile chain 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
*/
Miscellaneous cleanups to _mtx_lock_sleep(): - Declare some local variables at the top of the function instead of in a nested block. - Use mtx_owned() instead of masking off bits from mtx_lock manually. - Read the value of mtx_lock into 'v' as a separate line rather than inside an if statement for clarity. This code is hairy enough as it is.
2003-03-04 20:32:41 +00:00
if (v == MTX_UNOWNED) {
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_release(&m->mtx_object);
Instead of calling ia32_pause() conditionally on __i386__ or __amd64__ being defined, define and use a new MD macro, cpu_spinwait(). It only expands to something on i386 and amd64, so the compiled code should be identical. Name of the macro found by: jhb Reviewed by: jhb
2004-08-03 18:44:27 +00:00
cpu_spinwait();
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
continue;
- 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
}
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 a new kernel option MUTEX_WAKE_ALL that changes the mutex unlock code to awaken all waiters when a contested mutex is released instead of just the highest priority waiter. If the various threads are awakened in sequence then each thread may acquire and release the lock in question without contention resulting in fewer expensive unlock and lock operations. This old behavior of waking just the highest priority is still used if this option is specified. Making the algorithm conditional on a kernel option will allows us to benchmark both cases later and determine which one should be used by default. Requested by: tanimura-san
2004-04-06 19:12:24 +00:00
#ifdef MUTEX_WAKE_ALL
MPASS(v != MTX_CONTESTED);
#else
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
/*
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
* The mutex was marked contested on release. This means that
- Add comments about the maintenance of the per-thread list of contested locks held by each thread. - Fix a bug in the original BSD/OS code where a contested lock was not properly handed off from the old thread to the new thread when a contested lock with more than one blocked thread was transferred from one thread to another. - Don't use an atomic operation to write the MTX_CONTESTED value to mtx_lock in the aforementioned special case. The memory barriers and exclusion provided by sched_lock are sufficient. Spotted by: alc (2)
2003-07-02 16:14:09 +00:00
* there are other threads blocked on it. Grab ownership of
* it and propagate its priority to the current thread if
* necessary.
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
*/
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
if (v == MTX_CONTESTED) {
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
m->mtx_lock = tid | MTX_CONTESTED;
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_claim(&m->mtx_object);
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +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
}
Add a new kernel option MUTEX_WAKE_ALL that changes the mutex unlock code to awaken all waiters when a contested mutex is released instead of just the highest priority waiter. If the various threads are awakened in sequence then each thread may acquire and release the lock in question without contention resulting in fewer expensive unlock and lock operations. This old behavior of waking just the highest priority is still used if this option is specified. Making the algorithm conditional on a kernel option will allows us to benchmark both cases later and determine which one should be used by default. Requested by: tanimura-san
2004-04-06 19:12:24 +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
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
/*
* If the mutex isn't already contested and a failure occurs
* setting the contested bit, the mutex was either released
* or the state of the MTX_RECURSED bit changed.
*/
if ((v & MTX_CONTESTED) == 0 &&
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
!atomic_cmpset_ptr(&m->mtx_lock, v, v | MTX_CONTESTED)) {
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_release(&m->mtx_object);
Instead of calling ia32_pause() conditionally on __i386__ or __amd64__ being defined, define and use a new MD macro, cpu_spinwait(). It only expands to something on i386 and amd64, so the compiled code should be identical. Name of the macro found by: jhb Reviewed by: jhb
2004-08-03 18:44:27 +00:00
cpu_spinwait();
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
continue;
}
- 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
Enable ADAPTIVE_MUTEXES by default by changing the sense of the option to NO_ADAPTIVE_MUTEXES. This option has been enabled by default on amd64 for quite some time, and has been extensively tested on i386 and sparc64. It shows measurable performance gains in many circumstances, and few negative effects. It would be nice in t he future if adaptive mutexes actually went to sleep after a certain amount of spinning, but that will require quite a bit more testing.
2004-07-18 15:59:03 +00:00
#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
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
/*
* If the current owner of the lock is executing on another
* CPU, spin instead of blocking.
*/
owner = (struct thread *)(v & MTX_FLAGMASK);
Add "options ADAPTIVE_GIANT" which causes Giant to also be treated in an adaptive fashion when adaptive mutexes are enabled. The theory behind non-adaptive Giant is that Giant will be held for long periods of time, and therefore spinning waiting on it is wasteful. However, in MySQL benchmarks which are relatively Giant-free, running Giant adaptive makes an observable difference on SMP (5% transaction rate improvement). As such, make adaptive behavior on Giant an option so it can be more widely benchmarked.
2004-07-27 16:34:48 +00:00
#ifdef ADAPTIVE_GIANT
if (TD_IS_RUNNING(owner)) {
#else
Use TD_IS_RUNNING() instead of thread_running() in the adaptive mutex code.
2003-04-17 22:28:58 +00:00
if (m != &Giant && TD_IS_RUNNING(owner)) {
Add "options ADAPTIVE_GIANT" which causes Giant to also be treated in an adaptive fashion when adaptive mutexes are enabled. The theory behind non-adaptive Giant is that Giant will be held for long periods of time, and therefore spinning waiting on it is wasteful. However, in MySQL benchmarks which are relatively Giant-free, running Giant adaptive makes an observable difference on SMP (5% transaction rate improvement). As such, make adaptive behavior on Giant an option so it can be more widely benchmarked.
2004-07-27 16:34:48 +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
turnstile_release(&m->mtx_object);
Use TD_IS_RUNNING() instead of thread_running() in the adaptive mutex code.
2003-04-17 22:28:58 +00:00
while (mtx_owner(m) == owner && TD_IS_RUNNING(owner)) {
Instead of calling ia32_pause() conditionally on __i386__ or __amd64__ being defined, define and use a new MD macro, cpu_spinwait(). It only expands to something on i386 and amd64, so the compiled code should be identical. Name of the macro found by: jhb Reviewed by: jhb
2004-08-03 18:44:27 +00:00
cpu_spinwait();
Optimize the adaptive mutex spin a bit. Use a simple while loop with simple reads (and on IA32, a "pause" instruction for each interation of the loop) to spin until either the mutex owner field changes, or the lock owner stops executing. Suggested by: tanimura Tested on: i386
2002-06-04 21:53:48 +00:00
}
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
continue;
}
Enable ADAPTIVE_MUTEXES by default by changing the sense of the option to NO_ADAPTIVE_MUTEXES. This option has been enabled by default on amd64 for quite some time, and has been extensively tested on i386 and sparc64. It shows measurable performance gains in many circumstances, and few negative effects. It would be nice in t he future if adaptive mutexes actually went to sleep after a certain amount of spinning, but that will require quite a bit more testing.
2004-07-18 15:59:03 +00:00
#endif /* SMP && !NO_ADAPTIVE_MUTEXES */
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
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
/*
Spelling police.
2002-04-02 20:44:30 +00:00
* We definitely must sleep for this 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
*/
mtx_assert(m, MA_NOTOWNED);
- 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 a new KTR type KTR_CONTENTION, and use it in the mutex code to log the start and end of periods during which mtx_lock() is waiting to acquire a sleep mutex. The log message includes the file and line of both the waiter and the holder. Reviewed by: jhb, jake
2002-08-26 18:39:38 +00:00
#ifdef KTR
if (!cont_logged) {
CTR6(KTR_CONTENTION,
"contention: %p at %s:%d wants %s, taken by %s:%d",
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
(void *)tid, file, line, m->mtx_object.lo_name,
Add a new KTR type KTR_CONTENTION, and use it in the mutex code to log the start and end of periods during which mtx_lock() is waiting to acquire a sleep mutex. The log message includes the file and line of both the waiter and the holder. Reviewed by: jhb, jake
2002-08-26 18:39:38 +00:00
WITNESS_FILE(&m->mtx_object),
WITNESS_LINE(&m->mtx_object));
cont_logged = 1;
}
#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
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
* Block on the 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
*/
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_wait(&m->mtx_object, mtx_owner(m));
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 a new KTR type KTR_CONTENTION, and use it in the mutex code to log the start and end of periods during which mtx_lock() is waiting to acquire a sleep mutex. The log message includes the file and line of both the waiter and the holder. Reviewed by: jhb, jake
2002-08-26 18:39:38 +00:00
#ifdef KTR
if (cont_logged) {
CTR4(KTR_CONTENTION,
"contention end: %s acquired by %p at %s:%d",
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
m->mtx_object.lo_name, (void *)tid, file, line);
Add a new KTR type KTR_CONTENTION, and use it in the mutex code to log the start and end of periods during which mtx_lock() is waiting to acquire a sleep mutex. The log message includes the file and line of both the waiter and the holder. Reviewed by: jhb, jake
2002-08-26 18:39:38 +00:00
}
Add some basic support for measuring sleep mutex contention to the mutex profiling code. As with existing mutex profiling, measurement is done with respect to mtx_lock() instances in the code, as opposed to specific mutexes. In particular, measure two things: (1) Lock contention. How often did this mtx_lock() call get made and have to sleep (or almost sleep) waiting for the lock. This helps identify the "victims" of contention. (2) Hold contention. How often, while the lock was held by a thread as a result of this mtx_lock(), did another thread try to acquire the same mutex. This helps identify the causes of contention. I'm currently exploring adding measurement of "time waited for the lock", but the current implementation has proven useful to me so far so I figured I'd commit it so others could try it out. Note that this increases the size of mutexes when MUTEX_PROFILING is enabled, so you might find you need to further bump UMA_BOOT_PAGES. Fixes welcome. The once over: des, others
2004-01-25 01:59:27 +00:00
#endif
#ifdef MUTEX_PROFILING
if (contested)
m->mtx_contest_locking++;
m->mtx_contest_holding = 0;
Add a new KTR type KTR_CONTENTION, and use it in the mutex code to log the start and end of periods during which mtx_lock() is waiting to acquire a sleep mutex. The log message includes the file and line of both the waiter and the holder. Reviewed by: jhb, jake
2002-08-26 18:39:38 +00:00
#endif
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
return;
}
Rework the optimization for spinlocks on UP to be slightly less drastic and turn it back on. Specifically, the actual changes are now less intrusive in that the _get_spin_lock() and _rel_spin_lock() macros now have their contents changed for UP vs SMP kernels which centralizes the changes. Also, UP kernels do not use _mtx_lock_spin() and no longer include it. The UP versions of the spin lock functions do not use any atomic operations, but simple compares and stores which allow mtx_owned() to still work for spin locks while removing the overhead of atomic operations. Tested on: i386, alpha
2005-01-05 21:13:27 +00:00
#ifdef SMP
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
/*
* _mtx_lock_spin: the tougher part of acquiring an MTX_SPIN lock.
*
* This is only called if we need to actually spin for the lock. Recursion
* is handled inline.
*/
void
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
_mtx_lock_spin(struct mtx *m, uintptr_t tid, int opts, const char *file,
Cache the value of curthread in the _get_sleep_lock() and _get_spin_lock() macros and pass the value to the associated _mtx_*() functions to avoid more curthread dereferences in the function implementations. This provided a very modest perf improvement in some benchmarks. Suggested by: rwatson Tested by: scottl
2004-08-04 20:18:45 +00:00
int line)
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
{
int i = 0;
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
- 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
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spinning", m);
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
for (;;) {
Convert the atomic_ptr() operations over to operating on uintptr_t variables rather than void * variables. This makes it easier and simpler to get asm constraints and volatile keywords correct. MFC after: 3 days Tested on: i386, alpha, sparc64 Compiled on: ia64, powerpc, amd64 Kernel toolchain busted on: arm
2005-07-15 18:17:59 +00:00
if (_obtain_lock(m, tid))
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
break;
Exit and re-enter the critical section while spinning for a spinlock so that interrupts can come in while we are waiting for a lock.
2001-04-17 03:34:52 +00:00
/* Give interrupts a chance while we spin. */
Divorce critical sections from spinlocks. Critical sections as denoted by critical_enter() and critical_exit() are now solely a mechanism for deferring kernel preemptions. They no longer have any affect on interrupts. This means that standalone critical sections are now very cheap as they are simply unlocked integer increments and decrements for the common case. Spin mutexes now use a separate KPI implemented in MD code: spinlock_enter() and spinlock_exit(). This KPI is responsible for providing whatever MD guarantees are needed to ensure that a thread holding a spin lock won't be preempted by any other code that will try to lock the same lock. For now all archs continue to block interrupts in a "spinlock section" as they did formerly in all critical sections. Note that I've also taken this opportunity to push a few things into MD code rather than MI. For example, critical_fork_exit() no longer exists. Instead, MD code ensures that new threads have the correct state when they are created. Also, we no longer try to fixup the idlethreads for APs in MI code. Instead, each arch sets the initial curthread and adjusts the state of the idle thread it borrows in order to perform the initial context switch. This change is largely a big NOP, but the cleaner separation it provides will allow for more efficient alternative locking schemes in other parts of the kernel (bare critical sections rather than per-CPU spin mutexes for per-CPU data for example). Reviewed by: grehan, cognet, arch@, others Tested on: i386, alpha, sparc64, powerpc, arm, possibly more
2005-04-04 21:53:56 +00:00
spinlock_exit();
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
while (m->mtx_lock != MTX_UNOWNED) {
Add appropriate IA32 "pause" instructions to improve performanec on Pentium 4's and newer IA32 processors. The "pause" instruction has been verified by Intel to be a NOP on all currently existing IA32 processors prior to the Pentium 4.
2002-05-21 22:26:35 +00:00
if (i++ < 10000000) {
Instead of calling ia32_pause() conditionally on __i386__ or __amd64__ being defined, define and use a new MD macro, cpu_spinwait(). It only expands to something on i386 and amd64, so the compiled code should be identical. Name of the macro found by: jhb Reviewed by: jhb
2004-08-03 18:44:27 +00:00
cpu_spinwait();
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
continue;
Add appropriate IA32 "pause" instructions to improve performanec on Pentium 4's and newer IA32 processors. The "pause" instruction has been verified by Intel to be a NOP on all currently existing IA32 processors prior to the Pentium 4.
2002-05-21 22:26:35 +00:00
}
Fix an old cut 'n' paste bug inherited from BSD/OS: don't increment 'i' twice once we are in the long wait stage of spinning on a spin mutex.
2002-05-21 21:27:05 +00:00
if (i < 60000000)
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
DELAY(1);
Update for the KDB framework: o Make debugging code conditional upon KDB instead of DDB. o Call kdb_enter() instead of Debugger(). o Call kdb_backtrace() instead of db_print_backtrace() or backtrace(). kern_mutex.c: o Replace checks for db_active with checks for kdb_active and make them unconditional. kern_shutdown.c: o s/DDB_UNATTENDED/KDB_UNATTENDED/g o s/DDB_TRACE/KDB_TRACE/g o Save the TID of the thread doing the kernel dump so the debugger knows which thread to select as the current when debugging the kernel core file. o Clear kdb_active instead of db_active and do so unconditionally. o Remove backtrace() implementation. kern_synch.c: o Call kdb_reenter() instead of db_error().
2004-07-10 21:36:01 +00:00
else if (!kdb_active) {
If a spin lock is held for too long and WITNESS is enabled, then call witness_display_spinlock() to see if we can find out where the current owner of the spin lock last acquired the lock.
2003-07-31 18:52:18 +00:00
printf("spin lock %s held by %p for > 5 seconds\n",
Whitespace fixup, properly indent the body of an else clause.
2002-05-21 21:13:27 +00:00
m->mtx_object.lo_name, (void *)m->mtx_lock);
If a spin lock is held for too long and WITNESS is enabled, then call witness_display_spinlock() to see if we can find out where the current owner of the spin lock last acquired the lock.
2003-07-31 18:52:18 +00:00
#ifdef WITNESS
witness_display_spinlock(&m->mtx_object,
mtx_owner(m));
#endif
panic("spin lock held too long");
}
Instead of calling ia32_pause() conditionally on __i386__ or __amd64__ being defined, define and use a new MD macro, cpu_spinwait(). It only expands to something on i386 and amd64, so the compiled code should be identical. Name of the macro found by: jhb Reviewed by: jhb
2004-08-03 18:44:27 +00:00
cpu_spinwait();
- 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
}
Divorce critical sections from spinlocks. Critical sections as denoted by critical_enter() and critical_exit() are now solely a mechanism for deferring kernel preemptions. They no longer have any affect on interrupts. This means that standalone critical sections are now very cheap as they are simply unlocked integer increments and decrements for the common case. Spin mutexes now use a separate KPI implemented in MD code: spinlock_enter() and spinlock_exit(). This KPI is responsible for providing whatever MD guarantees are needed to ensure that a thread holding a spin lock won't be preempted by any other code that will try to lock the same lock. For now all archs continue to block interrupts in a "spinlock section" as they did formerly in all critical sections. Note that I've also taken this opportunity to push a few things into MD code rather than MI. For example, critical_fork_exit() no longer exists. Instead, MD code ensures that new threads have the correct state when they are created. Also, we no longer try to fixup the idlethreads for APs in MI code. Instead, each arch sets the initial curthread and adjusts the state of the idle thread it borrows in order to perform the initial context switch. This change is largely a big NOP, but the cleaner separation it provides will allow for more efficient alternative locking schemes in other parts of the kernel (bare critical sections rather than per-CPU spin mutexes for per-CPU data for example). Reviewed by: grehan, cognet, arch@, others Tested on: i386, alpha, sparc64, powerpc, arm, possibly more
2005-04-04 21:53:56 +00:00
spinlock_enter();
- 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
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
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
CTR1(KTR_LOCK, "_mtx_lock_spin: %p spin done", m);
return;
- 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 optimization for spinlocks on UP to be slightly less drastic and turn it back on. Specifically, the actual changes are now less intrusive in that the _get_spin_lock() and _rel_spin_lock() macros now have their contents changed for UP vs SMP kernels which centralizes the changes. Also, UP kernels do not use _mtx_lock_spin() and no longer include it. The UP versions of the spin lock functions do not use any atomic operations, but simple compares and stores which allow mtx_owned() to still work for spin locks while removing the overhead of atomic operations. Tested on: i386, alpha
2005-01-05 21:13:27 +00:00
#endif /* SMP */
- 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
/*
* _mtx_unlock_sleep: the tougher part of releasing an MTX_DEF lock.
*
* We are only called here if the lock is recursed or contested (i.e. we
* need to wake up a blocked thread).
*/
- 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
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
_mtx_unlock_sleep(struct mtx *m, int opts, const char *file, int line)
- 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;
Implement preemption of kernel threads natively in the scheduler rather than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)
2004-07-02 20:21:44 +00:00
#ifndef PREEMPTION
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;
Implement preemption of kernel threads natively in the scheduler rather than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)
2004-07-02 20:21:44 +00:00
#endif
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
if (mtx_recursed(m)) {
if (--(m->mtx_recurse) == 0)
atomic_clear_ptr(&m->mtx_lock, MTX_RECURSED);
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
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
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p unrecurse", m);
return;
}
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_lock(&m->mtx_object);
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 = turnstile_lookup(&m->mtx_object);
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
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
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p contested", m);
Now we have NO_ADAPTIVE_MUTEXES option, so use it here too. Missed by: scottl
2004-07-18 23:27:14 +00:00
#if defined(SMP) && !defined(NO_ADAPTIVE_MUTEXES)
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 (ts == NULL) {
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
_release_lock_quick(m);
if (LOCK_LOG_TEST(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p no sleepers", m);
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_release(&m->mtx_object);
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
return;
}
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
MPASS(ts != NULL);
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
#endif
Implement preemption of kernel threads natively in the scheduler rather than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)
2004-07-02 20:21:44 +00:00
#ifndef PREEMPTION
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
/* XXX */
td1 = turnstile_head(ts);
Implement preemption of kernel threads natively in the scheduler rather than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)
2004-07-02 20:21:44 +00:00
#endif
Add a new kernel option MUTEX_WAKE_ALL that changes the mutex unlock code to awaken all waiters when a contested mutex is released instead of just the highest priority waiter. If the various threads are awakened in sequence then each thread may acquire and release the lock in question without contention resulting in fewer expensive unlock and lock operations. This old behavior of waking just the highest priority is still used if this option is specified. Making the algorithm conditional on a kernel option will allows us to benchmark both cases later and determine which one should be used by default. Requested by: tanimura-san
2004-04-06 19:12:24 +00:00
#ifdef MUTEX_WAKE_ALL
turnstile_broadcast(ts);
_release_lock_quick(m);
#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
if (turnstile_signal(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
_release_lock_quick(m);
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
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
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p not held", m);
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 {
- Add comments about the maintenance of the per-thread list of contested locks held by each thread. - Fix a bug in the original BSD/OS code where a contested lock was not properly handed off from the old thread to the new thread when a contested lock with more than one blocked thread was transferred from one thread to another. - Don't use an atomic operation to write the MTX_CONTESTED value to mtx_lock in the aforementioned special case. The memory barriers and exclusion provided by sched_lock are sufficient. Spotted by: alc (2)
2003-07-02 16:14:09 +00:00
m->mtx_lock = MTX_CONTESTED;
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(&m->mtx_object, opts))
CTR1(KTR_LOCK, "_mtx_unlock_sleep: %p still contested",
m);
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 a new kernel option MUTEX_WAKE_ALL that changes the mutex unlock code to awaken all waiters when a contested mutex is released instead of just the highest priority waiter. If the various threads are awakened in sequence then each thread may acquire and release the lock in question without contention resulting in fewer expensive unlock and lock operations. This old behavior of waking just the highest priority is still used if this option is specified. Making the algorithm conditional on a kernel option will allows us to benchmark both cases later and determine which one should be used by default. Requested by: tanimura-san
2004-04-06 19:12:24 +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
turnstile_unpend(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
Implement preemption of kernel threads natively in the scheduler rather than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)
2004-07-02 20:21:44 +00:00
#ifndef PREEMPTION
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
/*
* XXX: This is just a hack until preemption is done. However,
* once preemption is done we need to either wrap the
* turnstile_signal() and release of the actual lock in an
* extra critical section or change the preemption code to
* always just set a flag and never do instant-preempts.
*/
td = curthread;
if (td->td_critnest > 0 || td1->td_priority >= td->td_priority)
commit the version I actually tested.. Submitted by: davidxu
2002-09-29 23:23:25 +00:00
return;
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(&sched_lock);
if (!TD_IS_RUNNING(td1)) {
- 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
#ifdef notyet
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->td_ithd != NULL) {
struct ithd *it = td->td_ithd;
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
if (it->it_interrupted) {
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
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
CTR2(KTR_LOCK,
- Axe RETIP() as it was very i386 specific and unwieldy. Instead, use the passed in filename and line number in the KTR tracepoint message. - Even though it is #if 0'd code, change the code to detect that a process is an interrupt thread to check p->p_ithd against NULL rather than checking non-existant process flags from BSD/OS. - Use '%p' to print pointers in KTR log messages instead of assuming sizeof(int) == sizeof(void *). - Don't set p_mtxname to NULL when releasing a mutex. It doesn't hurt to leave it set (we don't clear w_mesg for example) and at least at one time in the past, there used to be race conditions in the kernel that would result in setting this to NULL causing the kernel to dereference NULL. - Make the _mtx_assert() function be compiled in if INVARIANTS_SUPPORT is defined rather than if INVARIANTS is defined so that a KLD compiled with INVARIANTS that uses mtx_assert() can be used with a kernel that just has INVARIANT_SUPPORT compiled in.
2001-02-24 19:36:13 +00:00
"_mtx_unlock_sleep: %p interrupted %p",
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
it, it->it_interrupted);
intr_thd_fixup(it);
- 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
#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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
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
CTR2(KTR_LOCK,
"_mtx_unlock_sleep: %p switching out lock=%p", m,
(void *)m->mtx_lock);
- Change mi_switch() and sched_switch() to accept an optional thread to switch to. If a non-NULL thread pointer is passed in, then the CPU will switch to that thread directly rather than calling choosethread() to pick a thread to choose to. - Make sched_switch() aware of idle threads and know to do TD_SET_CAN_RUN() instead of sticking them on the run queue rather than requiring all callers of mi_switch() to know to do this if they can be called from an idlethread. - Move constants for arguments to mi_switch() and thread_single() out of the middle of the function prototypes and up above into their own section.
2004-07-02 19:09:50 +00:00
mi_switch(SW_INVOL, NULL);
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
if (LOCK_LOG_TEST(&m->mtx_object, opts))
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
CTR2(KTR_LOCK, "_mtx_unlock_sleep: %p resuming lock=%p",
m, (void *)m->mtx_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
mtx_unlock_spin(&sched_lock);
Implement preemption of kernel threads natively in the scheduler rather than as one-off hacks in various other parts of the kernel: - Add a function maybe_preempt() that is called from sched_add() to determine if a thread about to be added to a run queue should be preempted to directly. If it is not safe to preempt or if the new thread does not have a high enough priority, then the function returns false and sched_add() adds the thread to the run queue. If the thread should be preempted to but the current thread is in a nested critical section, then the flag TDF_OWEPREEMPT is set and the thread is added to the run queue. Otherwise, mi_switch() is called immediately and the thread is never added to the run queue since it is switch to directly. When exiting an outermost critical section, if TDF_OWEPREEMPT is set, then clear it and call mi_switch() to perform the deferred preemption. - Remove explicit preemption from ithread_schedule() as calling setrunqueue() now does all the correct work. This also removes the do_switch argument from ithread_schedule(). - Do not use the manual preemption code in mtx_unlock if the architecture supports native preemption. - Don't call mi_switch() in a loop during shutdown to give ithreads a chance to run if the architecture supports native preemption since the ithreads will just preempt DELAY(). - Don't call mi_switch() from the page zeroing idle thread for architectures that support native preemption as it is unnecessary. - Native preemption is enabled on the same archs that supported ithread preemption, namely alpha, i386, and amd64. This change should largely be a NOP for the default case as committed except that we will do fewer context switches in a few cases and will avoid the run queues completely when preempting. Approved by: scottl (with his re@ hat)
2004-07-02 20:21:44 +00:00
#endif
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
return;
- 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
/*
* All the unlocking of MTX_SPIN locks is done inline.
Whitespace cleanup.
2002-10-23 10:26:54 +00:00
* See the _rel_spin_lock() macro for the details.
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
*/
/*
- Axe RETIP() as it was very i386 specific and unwieldy. Instead, use the passed in filename and line number in the KTR tracepoint message. - Even though it is #if 0'd code, change the code to detect that a process is an interrupt thread to check p->p_ithd against NULL rather than checking non-existant process flags from BSD/OS. - Use '%p' to print pointers in KTR log messages instead of assuming sizeof(int) == sizeof(void *). - Don't set p_mtxname to NULL when releasing a mutex. It doesn't hurt to leave it set (we don't clear w_mesg for example) and at least at one time in the past, there used to be race conditions in the kernel that would result in setting this to NULL causing the kernel to dereference NULL. - Make the _mtx_assert() function be compiled in if INVARIANTS_SUPPORT is defined rather than if INVARIANTS is defined so that a KLD compiled with INVARIANTS that uses mtx_assert() can be used with a kernel that just has INVARIANT_SUPPORT compiled in.
2001-02-24 19:36:13 +00:00
* The backing function for the INVARIANTS-enabled mtx_assert()
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
*/
Grrr, s/INVARIANTS_SUPPORT/INVARIANT_SUPPORT/.
2001-02-24 21:29:32 +00:00
#ifdef INVARIANT_SUPPORT
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
Print correct file name and line number in mtx_assert(). Noticed by: jake
2001-01-22 05:56:55 +00:00
_mtx_assert(struct mtx *m, int what, const char *file, int line)
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
{
If we have already panic'd then don't bother enforcing mutex asserts as things are pretty much shot already and all panic'ing does is hurt our chances of getting a dump. Inspired by: sheldonh
2001-07-31 17:45:50 +00:00
Ignore mutex asserts when we're dumping as well. This allows me to panic a system from DDB when INVARIANTS is compiled into the kernel on a scsi system.
2005-07-30 05:54:30 +00:00
if (panicstr != NULL || dumping)
If we have already panic'd then don't bother enforcing mutex asserts as things are pretty much shot already and all panic'ing does is hurt our chances of getting a dump. Inspired by: sheldonh
2001-07-31 17:45:50 +00:00
return;
Remove brackets around variables in a function that used to be a macro.
2001-02-25 16:18:13 +00:00
switch (what) {
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
case MA_OWNED:
case MA_OWNED | MA_RECURSED:
case MA_OWNED | MA_NOTRECURSED:
Remove brackets around variables in a function that used to be a macro.
2001-02-25 16:18:13 +00:00
if (!mtx_owned(m))
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
panic("mutex %s not owned at %s:%d",
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
m->mtx_object.lo_name, file, line);
Remove brackets around variables in a function that used to be a macro.
2001-02-25 16:18:13 +00:00
if (mtx_recursed(m)) {
if ((what & MA_NOTRECURSED) != 0)
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
panic("mutex %s recursed at %s:%d",
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
m->mtx_object.lo_name, file, line);
Remove brackets around variables in a function that used to be a macro.
2001-02-25 16:18:13 +00:00
} else if ((what & MA_RECURSED) != 0) {
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
panic("mutex %s unrecursed at %s:%d",
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
m->mtx_object.lo_name, file, line);
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
}
break;
case MA_NOTOWNED:
Remove brackets around variables in a function that used to be a macro.
2001-02-25 16:18:13 +00:00
if (mtx_owned(m))
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
panic("mutex %s owned at %s:%d",
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
m->mtx_object.lo_name, file, line);
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
break;
default:
Print correct file name and line number in mtx_assert(). Noticed by: jake
2001-01-22 05:56:55 +00:00
panic("unknown mtx_assert at %s:%d", file, line);
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
}
}
#endif
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
/*
* The MUTEX_DEBUG-enabled mtx_validate()
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
*
* Most of these checks have been moved off into the LO_INITIALIZED flag
* maintained by the witness code.
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
#ifdef MUTEX_DEBUG
Remove __P.
2002-03-19 21:25:46 +00:00
void mtx_validate(struct mtx *);
- 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 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
void
mtx_validate(struct mtx *m)
- 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
{
Disable the kernacc() check in mtx_validate() until such time that kernacc does not require Giant. This means that we may miss panics on a class of mutex programming bugs, but only if running with a Chernobyl setting of debug-flags. Spotted by: Pete Carah <pete@ns.altadena.net>
2002-10-25 08:40:20 +00:00
/*
* XXX: When kernacc() does not require Giant we can reenable this check
*/
#ifdef notyet
- 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
/*
* XXX - When kernacc() is fixed on the alpha to handle K0_SEG memory properly
* we can re-enable the kernacc() checks.
*/
#ifndef __alpha__
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
/*
* Can't call kernacc() from early init386(), especially when
* initializing Giant mutex, because some stuff in kernacc()
* requires Giant itself.
Whitespace cleanup.
2002-10-23 10:26:54 +00:00
*/
*** empty log message ***
2001-08-24 22:53:45 +00:00
if (!cold)
if (!kernacc((caddr_t)m, sizeof(m),
VM_PROT_READ | VM_PROT_WRITE))
panic("Can't read and write to mutex %p", m);
- 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
#endif
Disable the kernacc() check in mtx_validate() until such time that kernacc does not require Giant. This means that we may miss panics on a class of mutex programming bugs, but only if running with a Chernobyl setting of debug-flags. Spotted by: Pete Carah <pete@ns.altadena.net>
2002-10-25 08:40:20 +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
}
#endif
- 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
/*
* General init routine used by the MTX_SYSINIT() macro.
*/
void
mtx_sysinit(void *arg)
{
struct mtx_args *margs = arg;
Change mtx_init() to now take an extra argument. The third argument is the generic lock type for use with witness. If this argument is NULL then the lock name is used as the lock type. Add a macro for a lock type name for network driver locks.
2002-04-04 20:52:27 +00:00
mtx_init(margs->ma_mtx, margs->ma_desc, NULL, margs->ma_opts);
- 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
}
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
/*
* Mutex initialization routine; initialize lock `m' of type contained in
Change mtx_init() to now take an extra argument. The third argument is the generic lock type for use with witness. If this argument is NULL then the lock name is used as the lock type. Add a macro for a lock type name for network driver locks.
2002-04-04 20:52:27 +00:00
* `opts' with options contained in `opts' and name `name.' The optional
* lock type `type' is used as a general lock category name for use with
* witness.
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
Change mtx_init() to now take an extra argument. The third argument is the generic lock type for use with witness. If this argument is NULL then the lock name is used as the lock type. Add a macro for a lock type name for network driver locks.
2002-04-04 20:52:27 +00:00
mtx_init(struct mtx *m, const char *name, const char *type, int opts)
- 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 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
struct lock_object *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
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
MPASS((opts & ~(MTX_SPIN | MTX_QUIET | MTX_RECURSE |
Axe the useless MTX_SLEEPABLE flag. mutexes are not sleepable locks. Nothing used this flag and WITNESS would have panic'd during mtx_init() if anything had.
2003-03-11 20:02:57 +00:00
MTX_NOWITNESS | MTX_DUPOK)) == 0);
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
#ifdef MUTEX_DEBUG
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
/* Diagnostic and error correction */
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
mtx_validate(m);
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
- 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 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
lock = &m->mtx_object;
The mtx_init() and sx_init() functions bzero'd locks before handing them off to witness_init() making the check for double intializating a lock by testing the LO_INITIALIZED flag moot. Workaround this by checking the LO_INITIALIZED flag ourself before we bzero the lock structure.
2001-10-20 01:22:42 +00:00
KASSERT((lock->lo_flags & LO_INITIALIZED) == 0,
Add "" around mutex name to make message less confusing.
2003-05-31 21:11:01 +00:00
("mutex \"%s\" %p already initialized", name, m));
The mtx_init() and sx_init() functions bzero'd locks before handing them off to witness_init() making the check for double intializating a lock by testing the LO_INITIALIZED flag moot. Workaround this by checking the LO_INITIALIZED flag ourself before we bzero the lock structure.
2001-10-20 01:22:42 +00:00
bzero(m, sizeof(*m));
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
if (opts & MTX_SPIN)
lock->lo_class = &lock_class_mtx_spin;
else
lock->lo_class = &lock_class_mtx_sleep;
Change mtx_init() to now take an extra argument. The third argument is the generic lock type for use with witness. If this argument is NULL then the lock name is used as the lock type. Add a macro for a lock type name for network driver locks.
2002-04-04 20:52:27 +00:00
lock->lo_name = name;
lock->lo_type = type != NULL ? type : name;
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
if (opts & MTX_QUIET)
lock->lo_flags = LO_QUIET;
if (opts & MTX_RECURSE)
lock->lo_flags |= LO_RECURSABLE;
if ((opts & MTX_NOWITNESS) == 0)
lock->lo_flags |= LO_WITNESS;
Add a new mtx_init option "MTX_DUPOK" which allows duplicate acquires of locks with this flag. Remove the dup_list and dup_ok code from subr_witness. Now we just check for the flag instead of doing string compares. Also, switch the process lock, process group lock, and uma per cpu locks over to this interface. The original mechanism did not work well for uma because per cpu lock names are unique to each zone. Approved by: jhb
2002-03-27 09:23:41 +00:00
if (opts & MTX_DUPOK)
lock->lo_flags |= LO_DUPOK;
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
m->mtx_lock = MTX_UNOWNED;
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 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
LOCK_LOG_INIT(lock, opts);
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 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
WITNESS_INIT(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
/*
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
* Remove lock `m' from all_mtx queue. We don't allow MTX_QUIET to be
* passed in as a flag here because if the corresponding mtx_init() was
* called with MTX_QUIET set, then it will already be set in the mutex's
* flags.
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
mtx_destroy(struct mtx *m)
{
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
LOCK_LOG_DESTROY(&m->mtx_object, 0);
- 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 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
if (!mtx_owned(m))
MPASS(mtx_unowned(m));
else {
Implement MTX_RECURSE flag for mtx_init(). All calls to mtx_init() for mutexes that recurse must now include the MTX_RECURSE bit in the flag argument variable. This change is in preparation for an upcoming (further) mutex API cleanup. The witness code will call panic() if a lock is found to recurse but the MTX_RECURSE bit was not set during the lock's initialization. The old MTX_RECURSE "state" bit (in mtx_lock) has been renamed to MTX_RECURSED, which is more appropriate given its meaning. The following locks have been made "recursive," thus far: eventhandler, Giant, callout, sched_lock, possibly some others declared in the architecture-specific code, all of the network card driver locks in pci/, as well as some other locks in dev/ stuff that I've found to be recursive. Reviewed by: jhb
2001-01-19 01:59:14 +00:00
MPASS((m->mtx_lock & (MTX_RECURSED|MTX_CONTESTED)) == 0);
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
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
/* Tell witness this isn't locked to make it happy. */
Change the preemption code for software interrupt thread schedules and mutex releases to not require flags for the cases when preemption is not allowed: The purpose of the MTX_NOSWITCH and SWI_NOSWITCH flags is to prevent switching to a higher priority thread on mutex releease and swi schedule, respectively when that switch is not safe. Now that the critical section API maintains a per-thread nesting count, the kernel can easily check whether or not it should switch without relying on flags from the programmer. This fixes a few bugs in that all current callers of swi_sched() used SWI_NOSWITCH, when in fact, only the ones called from fast interrupt handlers and the swi_sched of softclock needed this flag. Note that to ensure that swi_sched()'s in clock and fast interrupt handlers do not switch, these handlers have to be explicitly wrapped in critical_enter/exit pairs. Presently, just wrapping the handlers is sufficient, but in the future with the fully preemptive kernel, the interrupt must be EOI'd before critical_exit() is called. (critical_exit() can switch due to a deferred preemption in a fully preemptive kernel.) I've tested the changes to the interrupt code on i386 and alpha. I have not tested ia64, but the interrupt code is almost identical to the alpha code, so I expect it will work fine. PowerPC and ARM do not yet have interrupt code in the tree so they shouldn't be broken. Sparc64 is broken, but that's been ok'd by jake and tmm who will be fixing the interrupt code for sparc64 shortly. Reviewed by: peter Tested on: i386, alpha
2002-01-05 08:47:13 +00:00
WITNESS_UNLOCK(&m->mtx_object, LOP_EXCLUSIVE, __FILE__,
__LINE__);
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
}
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
WITNESS_DESTROY(&m->mtx_object);
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 mtx_lock_giant() and mtx_unlock_giant() wrappers for sysctl management of Giant during the Giant unwinding phase, and start work on instrumenting Giant for the file and proc mutexes. These wrappers allow developers to turn on and off Giant around various subsystems. DEVELOPERS SHOULD NEVER TURN OFF GIANT AROUND A SUBSYSTEM JUST BECAUSE THE SYSCTL EXISTS! General developers should only considering turning on Giant for a subsystem whos default is off (to help track down bugs). Only developers working on particular subsystems who know what they are doing should consider turning off Giant. These wrappers will greatly improve our ability to unwind Giant and test the kernel on a (mostly) subsystem by subsystem basis. They allow Giant unwinding developers (GUDs) to emplace appropriate subsystem and structural mutexes in the main tree and then request that the larger community test the work by turning off Giant around the subsystem(s), without the larger community having to mess around with patches. These wrappers also allow GUDs to boot into a (more likely to be) working system in the midst of their unwinding work and to test that work under more controlled circumstances. There is a master sysctl, kern.giant.all, which defaults to 0 (off). If turned on it overrides *ALL* other kern.giant sysctls and forces Giant to be turned on for all wrapped subsystems. If turned off then Giant around individual subsystems are controlled by various other kern.giant.XXX sysctls. Code which overlaps multiple subsystems must have all related subsystem Giant sysctls turned off in order to run without Giant.
2001-10-26 20:48:04 +00:00
- 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
/*
* Intialize the mutex code and system mutexes. This is called from the MD
* startup code prior to mi_startup(). The per-CPU data space needs to be
* setup before this is called.
*/
void
mutex_init(void)
{
/* Setup thread0 so that mutexes work. */
LIST_INIT(&thread0.td_contested);
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
/* Setup turnstiles so that sleep mutexes work. */
init_turnstiles();
- 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
/*
* Initialize mutexes.
*/
Change mtx_init() to now take an extra argument. The third argument is the generic lock type for use with witness. If this argument is NULL then the lock name is used as the lock type. Add a macro for a lock type name for network driver locks.
2002-04-04 20:52:27 +00:00
mtx_init(&Giant, "Giant", NULL, MTX_DEF | MTX_RECURSE);
mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
mtx_init(&proc0.p_mtx, "process lock", NULL, MTX_DEF | MTX_DUPOK);
- 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
mtx_lock(&Giant);
}
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