[PATCH] sched: avoid taking rq lock in wake_priority_sleeper
Avoid taking the request queue lock in wake_priority_sleeper if there are no
running processes.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Peter Williams <pwil3058@bigpond.net.au>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: "Siddha, Suresh B" <suresh.b.siddha@intel.com>
Cc: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/kernel/sched.c b/kernel/sched.c
index f04add9..fdd26ff 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2915,6 +2915,9 @@
int ret = 0;
#ifdef CONFIG_SCHED_SMT
+ if (!rq->nr_running)
+ return 0;
+
spin_lock(&rq->lock);
/*
* If an SMT sibling task has been put to sleep for priority