From: Balbir Singh <balbir@linux.vnet.ibm.com>
Date: Wed, 12 Nov 2008 10:49:00 +0000 (+0530)
Subject: sched: fix stale value in average load per task
X-Git-Tag: v2.6.28-rc5~23^2~1
X-Git-Url: http://www.pilppa.org/gitweb/gitweb.cgi?a=commitdiff_plain;h=a2d477778e82a60a0b7114cefdb70aa43af28782;p=linux-2.6-omap-h63xx.git

sched: fix stale value in average load per task

Impact: fix load balancer load average calculation accuracy

cpu_avg_load_per_task() returns a stale value when nr_running is 0.
It returns an older stale (caculated when nr_running was non zero) value.

This patch returns and sets rq->avg_load_per_task to zero when nr_running
is 0.

Compile and boot tested on a x86_64 box.

Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---

diff --git a/kernel/sched.c b/kernel/sched.c
index 50a21f96467..3bafbe350f4 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -1456,6 +1456,8 @@ static unsigned long cpu_avg_load_per_task(int cpu)
 
 	if (rq->nr_running)
 		rq->avg_load_per_task = rq->load.weight / rq->nr_running;
+	else
+		rq->avg_load_per_task = 0;
 
 	return rq->avg_load_per_task;
 }