[tip:sched/core] sched: Don't update shares twice on on_rq parent

From: tip-bot for Paul Turner
Date: Thu Jul 21 2011 - 14:28:39 EST

Commit-ID: 9598c82dcacadc3b9daa8170613fd054c6124d30
Gitweb: http://git.kernel.org/tip/9598c82dcacadc3b9daa8170613fd054c6124d30
Author: Paul Turner <pjt@xxxxxxxxxx>
AuthorDate: Wed, 6 Jul 2011 22:30:37 -0700
Committer: Ingo Molnar <mingo@xxxxxxx>
CommitDate: Thu, 21 Jul 2011 18:01:44 +0200

sched: Don't update shares twice on on_rq parent

In dequeue_task_fair() we bail on dequeue when we encounter a parenting entity
with additional weight. However, we perform a double shares update on this
entity as we continue the shares update traversal from this point, despite
dequeue_entity() having already updated its queuing cfs_rq.
Avoid this by starting from the parent when we resume.

Signed-off-by: Paul Turner <pjt@xxxxxxxxxx>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/20110707053059.797714697@xxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
kernel/sched_fair.c | 3 +++
1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index f88720b..6cdff84 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -1370,6 +1370,9 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
if (task_sleep && parent_entity(se))
+ /* avoid re-evaluating load for this entity */
+ se = parent_entity(se);
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/