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_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

lockdep.c

lockdep: Change mark_held_locks() to check hlock->check instead of lockdep_no_validate

2014-02-09 21:18:59 +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_common.h

sched/deadline: Add SCHED_DEADLINE inheritance logic

2014-01-13 13:42:56 +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

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_debug.c

locking: Move the spinlock code to kernel/locking/

2013-11-06 07:55:21 +01:00

spinlock.c

locking: Move the spinlock code to kernel/locking/

2013-11-06 07:55:21 +01:00