[PATCH 6/8] mutex: Extra reschedule point

[Peter Zijlstra]

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@xxxxxxxxxxxxx>
---
 kernel/locking/mutex.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -468,6 +468,13 @@ __mutex_lock_common(struct mutex *lock,
 	}
 	osq_unlock(&lock->osq);
 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 (unlikely(need_resched()))
+		schedule_preempt_disabled();
 #endif
 	spin_lock_mutex(&lock->wait_lock, flags);
 


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