[tip:sched/core] sched: Check the right ->nr_running in yield_task_fair()

tip-bot for Rik van Riel
2011-02-03T14:12:01Z

Commit-ID: 725e7580aaf98e9f7b22b8ccfc640ad0c09e2b08
Gitweb: http://git.kernel.org/tip/725e7580aaf98e9f7b22b8ccfc640ad0c09e2b08
Author: Rik van Riel <riel@redhat.com>
AuthorDate: Tue, 1 Feb 2011 09:47:15 -0500
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 3 Feb 2011 14:20:32 +0100

sched: Check the right ->nr_running in yield_task_fair()

With CONFIG_FAIR_GROUP_SCHED, each task_group has its own cfs_rq.
Yielding to a task from another cfs_rq may be worthwhile, since
a process calling yield typically cannot use the CPU right now.

Therefor, we want to check the per-cpu nr_running, not the
cgroup local one.

Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110201094715.798c4f86@annuminas.surriel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/sched_fair.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index 55040f3..4de9905 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1331,7 +1331,7 @@ static void yield_task_fair(struct rq *rq)
/*
* Are we the only task in the tree?
*/
- if (unlikely(cfs_rq->nr_running == 1))
+ if (unlikely(rq->nr_running == 1))
return;

clear_buddies(cfs_rq, se);