linux/kernel/locking
Jason Low 1d8fe7dc80 locking/mutexes: Unlock the mutex without the wait_lock
When running workloads that have high contention in mutexes on an 8 socket
machine, mutex spinners would often spin for a long time with no lock owner.

The main reason why this is occuring is in __mutex_unlock_common_slowpath(),
if __mutex_slowpath_needs_to_unlock(), then the owner needs to acquire the
mutex->wait_lock before releasing the mutex (setting lock->count to 1). When
the wait_lock is contended, this delays the mutex from being released.
We should be able to release the mutex without holding the wait_lock.

Signed-off-by: Jason Low <jason.low2@hp.com>
Cc: chegu_vinod@hp.com
Cc: paulmck@linux.vnet.ibm.com
Cc: Waiman.Long@hp.com
Cc: torvalds@linux-foundation.org
Cc: tglx@linutronix.de
Cc: riel@redhat.com
Cc: akpm@linux-foundation.org
Cc: davidlohr@hp.com
Cc: hpa@zytor.com
Cc: andi@firstfloor.org
Cc: aswin@hp.com
Cc: scott.norton@hp.com
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1390936396-3962-4-git-send-email-jason.low2@hp.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2014-03-11 12:14:54 +01:00
..
lglock.c locking: Move the lglocks code to kernel/locking/ 2013-11-06 09:24:20 +01:00
lockdep.c lockdep: Change mark_held_locks() to check hlock->check instead of lockdep_no_validate 2014-02-09 21:18:59 +01:00
lockdep_internals.h locking: Move the lockdep code to kernel/locking/ 2013-11-06 07:55:08 +01:00
lockdep_proc.c lockdep/proc: Fix lock-time avg computation 2013-11-11 12:41:34 +01:00
lockdep_states.h locking: Move the lockdep code to kernel/locking/ 2013-11-06 07:55:08 +01:00
Makefile locking: Move the percpu-rwsem code to kernel/locking/ 2013-11-06 09:24:22 +01:00
mcs_spinlock.h locking: Move mcs_spinlock.h into kernel/locking/ 2014-03-11 12:14:52 +01:00
mutex-debug.c mutexes: Give more informative mutex warning in the !lock->owner case 2013-12-17 15:35:10 +01:00
mutex-debug.h
mutex.c locking/mutexes: Unlock the mutex without the wait_lock 2014-03-11 12:14:54 +01:00
mutex.h
percpu-rwsem.c locking: Move the percpu-rwsem code to kernel/locking/ 2013-11-06 09:24:22 +01:00
rtmutex-debug.c rtmutex: Turn the plist into an rb-tree 2014-01-13 13:41:50 +01:00
rtmutex-debug.h locking: Move the rtmutex code to kernel/locking/ 2013-11-06 09:23:59 +01:00
rtmutex-tester.c locking: Move the rtmutex code to kernel/locking/ 2013-11-06 09:23:59 +01:00
rtmutex.c sched/deadline: Add SCHED_DEADLINE inheritance logic 2014-01-13 13:42:56 +01:00
rtmutex.h locking: Move the rtmutex code to kernel/locking/ 2013-11-06 09:23:59 +01:00
rtmutex_common.h sched/deadline: Add SCHED_DEADLINE inheritance logic 2014-01-13 13:42:56 +01:00
rwsem-spinlock.c locking: Move the rwsem code to kernel/locking/ 2013-11-06 09:24:18 +01:00
rwsem-xadd.c locking: Move the rwsem code to kernel/locking/ 2013-11-06 09:24:18 +01:00
rwsem.c locking: Move the rwsem code to kernel/locking/ 2013-11-06 09:24:18 +01:00
semaphore.c locking: Move the semaphore core to kernel/locking/ 2013-11-06 07:55:22 +01:00
spinlock.c locking: Move the spinlock code to kernel/locking/ 2013-11-06 07:55:21 +01:00
spinlock_debug.c locking: Move the spinlock code to kernel/locking/ 2013-11-06 07:55:21 +01:00