[patch 01/18] sched: (fixlet) dont update shares twice on on_rq parent

Paul Turner
2011-07-21T23:04:42Z

[-- Attachment #1: sched-bwc-fix_dequeue_task_buglet.patch --]
[-- Type: text/plain, Size: 898 bytes --]

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>
---
kernel/sched_fair.c | 3 +++
1 file changed, 3 insertions(+)

Index: tip/kernel/sched_fair.c
===================================================================
--- tip.orig/kernel/sched_fair.c
+++ tip/kernel/sched_fair.c
@@ -1370,6 +1370,9 @@ static void dequeue_task_fair(struct rq
*/
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;