locking/mutexes: Add extra reschedule point
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>
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 2670b84..02c61a9 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -468,6 +468,13 @@
}
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 (need_resched())
+ schedule_preempt_disabled();
#endif
spin_lock_mutex(&lock->wait_lock, flags);
