linux-kernel - [patch v5 13/15] sched: no balance for prefer

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Message-Id: <1361164062-20111-14-git-send-email-alex.shi@intel.com>
Date:	Mon, 18 Feb 2013 13:07:40 +0800
From:	Alex Shi <alex.shi@...el.com>
To:	torvalds@...ux-foundation.org, mingo@...hat.com,
	peterz@...radead.org, tglx@...utronix.de,
	akpm@...ux-foundation.org, arjan@...ux.intel.com, bp@...en8.de,
	pjt@...gle.com, namhyung@...nel.org, efault@....de
Cc:	vincent.guittot@...aro.org, gregkh@...uxfoundation.org,
	preeti@...ux.vnet.ibm.com, viresh.kumar@...aro.org,
	linux-kernel@...r.kernel.org, alex.shi@...el.com,
	morten.rasmussen@....com
Subject: [patch v5 13/15] sched: no balance for prefer_sibling in power scheduling

In power aware scheduling, we don't want to balance 'prefer_sibling'
groups just because local group has capacity.
If the local group has no tasks at the time, that is the power
balance hope so.

Signed-off-by: Alex Shi <alex.shi@...el.com>
---
 kernel/sched/fair.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index f3abb83..ffdf35d 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4782,8 +4782,12 @@ static inline void update_sd_lb_stats(struct lb_env *env,
 		 * extra check prevents the case where you always pull from the
 		 * heaviest group when it is already under-utilized (possible
 		 * with a large weight task outweighs the tasks on the system).
+		 *
+		 * In power aware scheduling, we don't care load weight and
+		 * want not to pull tasks just because local group has capacity.
 		 */
-		if (prefer_sibling && !local_group && sds->this_has_capacity)
+		if (prefer_sibling && !local_group && sds->this_has_capacity
+				&& env->perf_lb)
 			sgs.group_capacity = min(sgs.group_capacity, 1UL);
 
 		if (local_group) {
-- 
1.7.12

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