Commit Graph

205 Commits

Author SHA1 Message Date
John Baldwin
ad69e26b69 Add KASSERT()'s to catch attempts to recurse on spin mutexes that aren't
marked recursable either via mtx_lock_spin() or thread_lock().

MFC after:	1 week
2008-02-13 23:39:05 +00:00
John Baldwin
13c85a48df Add a couple of assertions and KTR logging to thread_lock_flags() to
match mtx_lock_spin_flags().

MFC after:	1 week
2008-02-13 23:33:50 +00:00
Jeff Roberson
eea4f254fe - Re-implement lock profiling in such a way that it no longer breaks
the ABI when enabled.  There is no longer an embedded lock_profile_object
   in each lock.  Instead a list of lock_profile_objects is kept per-thread
   for each lock it may own.  The cnt_hold statistic is now always 0 to
   facilitate this.
 - Support shared locking by tracking individual lock instances and
   statistics in the per-thread per-instance lock_profile_object.
 - Make the lock profiling hash table a per-cpu singly linked list with a
   per-cpu static lock_prof allocator.  This removes the need for an array
   of spinlocks and reduces cache contention between cores.
 - Use a seperate hash for spinlocks and other locks so that only a
   critical_enter() is required and not a spinlock_enter() to modify the
   per-cpu tables.
 - Count time spent spinning in the lock statistics.
 - Remove the LOCK_PROFILE_SHARED option as it is always supported now.
 - Specifically drop and release the scheduler locks in both schedulers
   since we track owners now.

In collaboration with:	Kip Macy
Sponsored by:	Nokia
2007-12-15 23:13:31 +00:00
Attilio Rao
573c6b82df Make ADAPTIVE_GIANT as the default in the kernel and remove the option.
Currently, Giant is not too much contented so that it is ok to treact it
like any other mutexes.

Please don't forget to update your own custom config kernel files.

Approved by:	cognet, marcel (maintainers of arches where option is
		not enabled at the moment)
2007-11-28 05:50:45 +00:00
Attilio Rao
49aead8a10 Simplify the adaptive spinning algorithm in rwlock and mutex:
currently, before to spin the turnstile spinlock is acquired and the
waiters flag is set.
This is not strictly necessary, so just spin before to acquire the
spinlock and to set the flags.
This will simplify a lot other functions too, as now we have the waiters
flag set only if there are actually waiters.
This should make wakeup/sleeping couplet faster under intensive mutex
workload.
This also fixes a bug in rw_try_upgrade() in the adaptive case, where
turnstile_lookup() will recurse on the ts_lock lock that will never be
really released [1].

[1] Reported by: jeff with Nokia help
Tested by: pho, kris (earlier, bugged version of rwlock part)
Discussed with: jhb [2], jeff
MFC after: 1 week

[2] John had a similar patch about 6.x and/or 7.x about mutexes probabilly
2007-11-26 22:37:35 +00:00
Attilio Rao
f9721b43ed Expand lock class with the "virtual" function lc_assert which will offer
an unified way for all the lock primitives to express lock assertions.
Currenty, lockmgrs and rmlocks don't have assertions, so just panic in
that case.
This will be a base for more callout improvements.

Ok'ed by: jhb, jeff
2007-11-18 14:43:53 +00:00
Julian Elischer
431f890614 generally we are interested in what thread did something as
opposed to what process. Since threads by default have teh name of the
process unless over-written with more useful information, just print the
thread name instead.
2007-11-14 06:21:24 +00:00
Jeff Roberson
6ea38de8aa - Remove the global definition of sched_lock in mutex.h to break
new code and third party modules which try to depend on it.
 - Initialize sched_lock in sched_4bsd.c.
 - Declare sched_lock in sparc64 pmap.c and assert that we're compiling
   with SCHED_4BSD to prevent accidental crashes from running ULE.  This
   is the sole remaining file outside of the scheduler that uses the
   global sched_lock.

Approved by:	re
2007-07-18 20:46:06 +00:00
Jeff Roberson
773890b9a8 - Add the proper lock profiling calls to _thread_lock().
Obtained from:	kipmacy
Approved by:	re
2007-07-18 20:38:13 +00:00
Matt Jacob
65d32cd8fb Propagate volatile qualifier to make gcc4.2 happy. 2007-06-09 18:09:37 +00:00
Attilio Rao
e682569165 Remove the MUTEX_WAKE_ALL option and make it the default behaviour for our
mutexes.
Currently we alredy force MUTEX_WAKE_ALL beacause of some problems with the
!MUTEX_WAKE_ALL case (unavioidable priority inversion).
2007-06-08 21:36:52 +00:00
Jeff Roberson
710eacdc5f - Placing the 'volatile' on the right side of the * in the td_lock
declaration removes the need for __DEVOLATILE().

Pointed out by:	tegge
2007-06-06 03:40:47 +00:00
Attilio Rao
d301eb10c7 Fix a problem with not-preemptive kernels caming from mis-merging of
existing code with the new thread_lock patch.
This also cleans up a bit unlock operation for mutexes.

Approved by: jhb, jeff(mentor)
2007-06-05 18:57:09 +00:00
Konstantin Belousov
b95b98b0bd Restore non-SMP build.
Reviewed by:	attilio
2007-06-05 14:20:13 +00:00
Jeff Roberson
2502c107ba Commit 3/14 of sched_lock decomposition.
- Add a per-turnstile spinlock to solve potential priority propagation
   deadlocks that are possible with thread_lock().
 - The turnstile lock order is defined as the exact opposite of the
   lock order used with the sleep locks they represent.  This allows us
   to walk in reverse order in priority_propagate and this is the only
   place we wish to multiply acquire turnstile locks.
 - Use the turnstile_chain lock to protect assigning mutexes to turnstiles.
 - Change the turnstile interface to pass back turnstile pointers to the
   consumers.  This allows us to reduce some locking and makes it easier
   to cancel turnstile assignment while the turnstile chain lock is held.

Tested by:      kris, current@
Tested on:      i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc.
Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
2007-06-04 23:51:44 +00:00
John Baldwin
c91fcee75d Move lock_profile_object_{init,destroy}() into lock_{init,destroy}(). 2007-05-18 15:04:59 +00:00
John Baldwin
c0bfd70306 Teach 'show lock' to properly handle a destroyed mutex. 2007-05-08 21:50:46 +00:00
Kip Macy
70fe8436c8 move lock_profile calls out of the macros and into kern_mutex.c
add check for mtx_recurse == 0 when releasing sleep lock
2007-04-03 22:52:31 +00:00
John Baldwin
cd6e6e4e11 - Simplify the #ifdef's for adaptive mutexes and rwlocks by conditionally
defining a macro earlier in the file.
- Add NO_ADAPTIVE_RWLOCKS option to disable adaptive spinning for rwlocks.
2007-03-22 16:09:23 +00:00
John Baldwin
aa89d8cd52 Rename the 'mtx_object', 'rw_object', and 'sx_object' members of mutexes,
rwlocks, and sx locks to 'lock_object'.
2007-03-21 21:20:51 +00:00
John Baldwin
6e21afd40c Add two new function pointers 'lc_lock' and 'lc_unlock' to lock classes.
These functions are intended to be used to drop a lock and then reacquire
it when doing an sleep such as msleep(9).  Both functions accept a
'struct lock_object *' as their first parameter.  The 'lc_unlock' function
returns an integer that is then passed as the second paramter to the
subsequent 'lc_lock' function.  This can be used to communicate state.
For example, sx locks and rwlocks use this to indicate if the lock was
share/read locked vs exclusive/write locked.

Currently, spin mutexes and lockmgr locks do not provide working lc_lock
and lc_unlock functions.
2007-03-09 16:27:11 +00:00
John Baldwin
ae8dde30c2 Use C99-style struct member initialization for lock classes. 2007-03-09 16:04:44 +00:00
Kip Macy
c66d760608 lock stats updates need to be protected by the lock 2007-03-02 07:21:20 +00:00
Kip Macy
a5bceb77f2 Evidently I've overestimated gcc's ability to peak inside inline functions
and optimize away unused stack values. The 48 bytes that the lock_profile_object
adds to the stack evidently has a measurable performance impact on certain workloads.
2007-03-01 09:35:48 +00:00
Kip Macy
f183910b97 Further improvements to LOCK_PROFILING:
- Fix missing initialization in kern_rwlock.c causing bogus times to be collected
 - Move updates to the lock hash to after the lock is released for spin mutexes,
   sleep mutexes, and sx locks
 - Add new kernel build option LOCK_PROFILE_FAST - only update lock profiling
   statistics when an acquisition is contended. This reduces the overhead of
   LOCK_PROFILING to increasing system time by 20%-25% which on
   "make -j8 kernel-toolchain" on a dual woodcrest is unmeasurable in terms
   of wall-clock time. Contrast this to enabling lock profiling without
   LOCK_PROFILE_FAST and I see a 5x-6x slowdown in wall-clock time.
2007-02-27 06:42:05 +00:00
Kip Macy
fe68a91631 general LOCK_PROFILING cleanup
- only collect timestamps when a lock is contested - this reduces the overhead
  of collecting profiles from 20x to 5x

- remove unused function from subr_lock.c

- generalize cnt_hold and cnt_lock statistics to be kept for all locks

- NOTE: rwlock profiling generates invalid statistics (and most likely always has)
  someone familiar with that should review
2007-02-26 08:26:44 +00:00
Kip Macy
1364a812e7 - Fix some gcc warnings in lock_profile.h
- add cnt_hold cnt_lock support for spin mutexes
- make sure contested is initialized to zero to only bump contested when appropriate
- move initialization function to kern_mutex.c to avoid cyclic dependency between
  mutex.h and lock_profile.h
2006-12-16 02:37:58 +00:00
Kip Macy
61bd5e21b3 track lock class name in a way that doesn't break WITNESS 2006-11-13 05:41:46 +00:00
Kip Macy
7c0435b933 MUTEX_PROFILING has been generalized to LOCK_PROFILING. We now profile
wait (time waited to acquire) and hold times for *all* kernel locks. If
the architecture has a system synchronized TSC, the profiling code will
use that - thereby minimizing profiling overhead. Large chunks of profiling
code have been moved out of line, the overhead measured on the T1 for when
it is compiled in but not enabled is < 1%.

Approved by: scottl (standing in for mentor rwatson)
Reviewed by: des and jhb
2006-11-11 03:18:07 +00:00
John Baldwin
0fa2168b19 - When spinning on a spin lock, if the debugger is active or we are in a
panic, go ahead and do the longer DELAY(1) spin wait.
- If we panic due to spinning too long, print out a few more details
  including the pointer to the mutex in question and the tid of the owning
  thread.
2006-08-15 18:26:12 +00:00
John Baldwin
764e4d54e9 Adjust td_locks for non-spin mutexes, rwlocks, and sx locks so that it is
a count of all non-spin locks, not just lockmgr locks.  This can give us a
much cheaper way to see if we have any locks held (such as when returning
to userland via userret()) without requiring WITNESS.

MFC after:	1 week
2006-07-27 21:45:55 +00:00
John Baldwin
186abbd727 Write a magic value into mtx_lock when destroying a mutex that will force
all other mtx_lock() operations to block.  Previously, when the mutex was
destroyed, it would still have a valid value in mtx_lock(): either the
unowned cookie, which would allow a subsequent mtx_lock() to succeed, or a
pointer to the thread who destroyed the mutex if the mutex was locked when
it was destroyed.

MFC after:	3 days
2006-07-27 19:58:18 +00:00
John Baldwin
49b94bfc54 Bah, fix fat finger in last. Invert the ~ on MTX_FLAGMASK as it's
non-intuitive for the ~ to be built into the mask.  All the users now
explicitly ~ the mask.  In addition, add MTX_UNOWNED to the mask even
though it technically isn't a flag.  This should unbreak mtx_owner().

Quickly spotted by:	kris
2006-06-03 21:11:33 +00:00
John Baldwin
315ce35f7b Simplify mtx_owner() so it only reads m->mtx_lock once. 2006-06-03 20:45:00 +00:00
John Baldwin
f781b5a4bb Style fix to be more like _mtx_lock_sleep(): use 'while (!foo) { ... }'
instead of 'for (;;) { if (foo) break; ... }'.
2006-06-03 20:44:01 +00:00
Poul-Henning Kamp
c40da00ca3 Since DELAY() was moved, most <machine/clock.h> #includes have been
unnecessary.
2006-05-16 14:37:58 +00:00
John Baldwin
73dbd3da73 Remove various bits of conditional Alpha code and fixup a few comments. 2006-05-12 05:04:46 +00:00
John Baldwin
76447e5618 Mark the thread pointer used during an adaptive spin volatile so that the
compiler doesn't decide to cache td_state.  Cachine the state would cause
the spinning thread to not notice when the owning thread stopped executing
(if it was preempted for example) which could result in livelock.
2006-04-14 19:51:50 +00:00
John Baldwin
7aa4f6852a - Add support for having both a shared and exclusive queue of threads in
each turnstile.  Also, allow for the owner thread pointer of a turnstile
  to be NULL.  This is needed for the upcoming reader/writer lock
  implementation.
- Add a new ddb command 'show turnstile' that will look up the turnstile
  associated with the given lock argument and display useful information
  like the list of threads blocked on each queue, etc.  If there isn't an
  active turnstile for a lock at the specified address, then the function
  will see if there is an active turnstile at the specified address and
  display info about it if so.
- Adjust the mutex code to handle the turnstile API changes.

Tested on:	i386 (all), alpha, amd64, sparc64 (1 and 3)
2006-01-27 22:42:12 +00:00
John Baldwin
67f7fe8c01 Whitespace fix. 2006-01-24 22:24:05 +00:00
John Baldwin
83a81bcb14 Add a new file (kern/subr_lock.c) for holding code related to struct
lock_obj objects:
- Add new lock_init() and lock_destroy() functions to setup and teardown
  lock_object objects including KTR logging and registering with WITNESS.
- Move all the handling of LO_INITIALIZED out of witness and the various
  lock init functions into lock_init() and lock_destroy().
- Remove the constants for static indices into the lock_classes[] array
  and change the code outside of subr_lock.c to use LOCK_CLASS to compare
  against a known lock class.
- Move the 'show lock' ddb function and lock_classes[] array out of
  kern_mutex.c over to subr_lock.c.
2006-01-17 16:55:17 +00:00
John Baldwin
550d1c9392 Initialize thread0.td_contested in init_turnstiles() rather than
mutex_init() as it is used by the turnstile code and is not mutex-specific.
2006-01-17 16:47:42 +00:00
Scott Long
861a23087b If destroying a spinlock, make sure that it is exited properly.
Submitted by: jhb
MFC After: 3 days
2006-01-08 00:18:34 +00:00
John Baldwin
3b783acd2a Revert an untested local change that crept in with the lo_class changes
and subsequently broke the build.  This change is supposed to fix the
case where doing a mtx_destroy() off a spin mutex while you hold it fails.
If it had been tested I would just leave it in, but it hasn't been tested
yet, so it will have to wait until later.
2006-01-07 14:03:15 +00:00
Tai-hwa Liang
75d6a87fa3 Trying to fix compilation bustage introduced in rev1.160 by converting
a missing lo_class to LO_CLASSINDEX().
2006-01-07 02:07:08 +00:00
John Baldwin
3c6decc327 Trim another pointer from struct lock_object (and thus from struct mtx and
struct sx).  Instead of storing a direct pointer to a our lock_class
struct in lock_object, reserve 4 bits in the lo_flags field to serve as an
index into a global lock_classes array that contains pointers to the lock
classes.  Only debugging code such as WITNESS or INVARIANTS checks and KTR
logging need to access the lock_class member, so this shouldn't add any
overhead to production kernels.  It might add some slight overhead to
kernels using those debug options however.

As with the previous set of changes to lock_object, this is going to
completely obliterate the kernel ABI, so be sure to recompile all your
modules.
2006-01-06 18:07:32 +00:00
John Baldwin
d272fe53a4 Add a new 'show lock' command to ddb. If the argument has a valid lock
class, then it displays various information about the lock and calls a
new function pointer in lock_class (lc_ddb_show) to dump class-specific
information about the lock as well (such as the owner of a mutex or
xlock'ed sx lock).  This is easier than staring at hex dumps of locks to
figure out who owns the lock, etc.  Note that extending lock_class doesn't
affect the ABI for any kernel modules as the only code that deals with
lock_class structures directly is kern_mutex.c, kern_sx.c, and witness.

MFC after:	1 week
2005-12-13 23:14:35 +00:00
John Baldwin
8c4b6380c7 Move the initialization of the devmtx into the mutex_init() function
called during early init before cninit().

Tested on:	i386, alpha, sparc64
Reviewed by:	phk, imp
Reported by:	Divacky Roman xdivac02 at stud dot fit dot vutbr dot cz
MFC after:	1 week
2005-10-18 18:27:44 +00:00
John Baldwin
83cece6fa1 - Add an assertion to panic if one tries to call mtx_trylock() on a spin
mutex.
- Don't panic if a spin lock is held too long inside _mtx_lock_spin() if
  panicstr is set (meaning that we are already in a panic).  Just keep
  spinning forever instead.
2005-09-02 20:21:49 +00:00
Paul Saab
1126349ae7 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