[tip:sched/urgent] sched: Fix idle balancing

[tip-bot for Nikhil Rao <ncrao@google.com>]

Commit-ID:  d5ad140bc1505a98c0f040937125bfcbb508078f
Gitweb:     http://git.kernel.org/tip/d5ad140bc1505a98c0f040937125bfcbb508078f
Author:     Nikhil Rao <ncrao@google.com>
AuthorDate: Wed, 17 Nov 2010 11:42:04 -0800
Committer:  Ingo Molnar <mingo@elte.hu>
CommitDate: Thu, 18 Nov 2010 13:12:33 +0100

sched: Fix idle balancing

An earlier commit reverts idle balancing throttling reset to fix a 30%
regression in volanomark throughput. We still need to reset idle_stamp
when we pull a task in newidle balance.

Reported-by: Alex Shi <alex.shi@intel.com>
Signed-off-by: Nikhil Rao <ncrao@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1290022924-3548-1-git-send-email-ncrao@google.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 kernel/sched_fair.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c
index ba0556d..00ebd76 100644
--- a/kernel/sched_fair.c
+++ b/kernel/sched_fair.c
@@ -3215,8 +3215,10 @@ static void idle_balance(int this_cpu, struct rq *this_rq)
 		interval = msecs_to_jiffies(sd->balance_interval);
 		if (time_after(next_balance, sd->last_balance + interval))
 			next_balance = sd->last_balance + interval;
-		if (pulled_task)
+		if (pulled_task) {
+			this_rq->idle_stamp = 0;
 			break;
+		}
 	}
 
 	raw_spin_lock(&this_rq->lock);