From: Paul Turner <pjt@google.com>
Date: Thu, 7 Jul 2011 05:30:37 +0000 (-0700)
Subject: sched: Don't update shares twice on on_rq parent
X-Git-Tag: v3.1-rc1~298^2~8
X-Git-Url: https://asedeno.scripts.mit.edu/gitweb/?a=commitdiff_plain;h=9598c82dcacadc3b9daa8170613fd054c6124d30;p=linux.git

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@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110707053059.797714697@google.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index f88720b3df8b..6cdff849fc19 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))
 				set_next_buddy(parent_entity(se));
+
+			/* avoid re-evaluating load for this entity */
+			se = parent_entity(se);
 			break;
 		}
 		flags |= DEQUEUE_SLEEP;