linux-kernel - [RFC][PATCH 3/9] sched: Make select_idle_sibling() skip cpu with a cpu

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Message-Id: <1373385338-12983-4-git-send-email-morten.rasmussen@arm.com>
Date:	Tue,  9 Jul 2013 16:55:32 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	mingo@...nel.org, peterz@...radead.org
Cc:	arjan@...ux.intel.com, vincent.guittot@...aro.org,
	preeti@...ux.vnet.ibm.com, alex.shi@...el.com, efault@....de,
	pjt@...gle.com, len.brown@...el.com, corbet@....net,
	akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
	tglx@...utronix.de, catalin.marinas@....com,
	linux-kernel@...r.kernel.org, linaro-kernel@...ts.linaro.org,
	morten.rasmussen@....com
Subject: [RFC][PATCH 3/9] sched: Make select_idle_sibling() skip cpu with a cpu_power of 1

select_idle_sibling() must disregard cpus with cpu_power=1 to avoid using
cpus disabled by the power scheduler.

This is a quick fix. The algorithm should be updated to handle cpu_power=1
properly.

Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
CC: Ingo Molnar <mingo@...nel.org>
CC: Peter Zijlstra <peterz@...radead.org>
CC: Catalin Marinas <catalin.marinas@....com>
---
 kernel/sched/fair.c |    8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 01f1f26..f637ea5 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -3287,13 +3287,14 @@ static int select_idle_sibling(struct task_struct *p, int target)
 	struct sched_group *sg;
 	int i = task_cpu(p);
 
-	if (idle_cpu(target))
+	if (idle_cpu(target) && power_cpu_balance(target))
 		return target;
 
 	/*
 	 * If the prevous cpu is cache affine and idle, don't be stupid.
 	 */
-	if (i != target && cpus_share_cache(i, target) && idle_cpu(i))
+	if (i != target && cpus_share_cache(i, target) && idle_cpu(i) &&
+		power_cpu_balance(i))
 		return i;
 
 	/*
@@ -3308,7 +3309,8 @@ static int select_idle_sibling(struct task_struct *p, int target)
 				goto next;
 
 			for_each_cpu(i, sched_group_cpus(sg)) {
-				if (i == target || !idle_cpu(i))
+				if (i == target || !idle_cpu(i) ||
+					!power_cpu_balance(i))
 					goto next;
 			}
 
-- 
1.7.9.5


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