linux-kernel - [tip:sched/numa] sched/numa: Fix NUMA_PULL

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Date:	Fri, 12 Oct 2012 04:26:47 -0700
From:	tip-bot for Peter Zijlstra <a.p.zijlstra@...llo.nl>
To:	linux-tip-commits@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, hpa@...or.com, mingo@...nel.org,
	a.p.zijlstra@...llo.nl, tglx@...utronix.de
Subject: [tip:sched/numa] sched/numa: Fix NUMA_PULL_BIAS

Commit-ID:  5b1e7a5858fd9cbf5b2062d845db54b1750c6ca6
Gitweb:     http://git.kernel.org/tip/5b1e7a5858fd9cbf5b2062d845db54b1750c6ca6
Author:     Peter Zijlstra <a.p.zijlstra@...llo.nl>
AuthorDate: Fri, 5 Oct 2012 15:57:54 +0200
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Fri, 12 Oct 2012 12:07:17 +0200

sched/numa: Fix NUMA_PULL_BIAS

PULL_BIAS is broken, the intent was to only attempt a small bias when
the machine was otherwise balanced, hence the out_balanced label.

The problem is that a number of branches that decide we're completely
unbalanced also jump to the out_balanced label, causing undue numa
bias. The end result was that an unbalanced system of 8:1 would try
and move the 1 task towards the 8.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/n/tip-3pzp0o6gemhb8t7fj8shscpo@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/fair.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 62d77ef..60be6bf 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4569,7 +4569,7 @@ find_busiest_group(struct lb_env *env, int *balance)
 
 	/* There is no busy sibling group to pull tasks from */
 	if (!sds.busiest || sds.busiest_nr_running == 0)
-		goto out_balanced;
+		goto ret;
 
 	sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
 
@@ -4591,14 +4591,14 @@ find_busiest_group(struct lb_env *env, int *balance)
 	 * don't try and pull any tasks.
 	 */
 	if (sds.this_load >= sds.max_load)
-		goto out_balanced;
+		goto ret;
 
 	/*
 	 * Don't pull any tasks if this group is already above the domain
 	 * average load.
 	 */
 	if (sds.this_load >= sds.avg_load)
-		goto out_balanced;
+		goto ret;
 
 	if (env->idle == CPU_IDLE) {
 		/*
--
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