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locking/mutexes: Add extra reschedule point

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Add in an extra reschedule in an attempt to avoid getting reschedule
the moment we've acquired the lock.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-zah5eyn9gu7qlgwh9r6n2anc@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2014-02-03 16:21:09 +01:00 • committed by Ingo Molnar
commit 34c6bc2c91
1 changed files with 7 additions and 0 deletions
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7
kernel/locking/mutex.c
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@ -468,6 +468,13 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
} }
osq_unlock(&lock->osq); osq_unlock(&lock->osq);
slowpath: slowpath:
/*
* If we fell out of the spin path because of need_resched(),
* reschedule now, before we try-lock the mutex. This avoids getting
* scheduled out right after we obtained the mutex.
*/
if (need_resched())
schedule_preempt_disabled();
#endif #endif
spin_lock_mutex(&lock->wait_lock, flags); spin_lock_mutex(&lock->wait_lock, flags);