linux-kernel - [tip:sched/core] sched/core: Enable SD_BALANCE

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Message-ID: <tip-9ee1cda5ee25c7dd82acf25892e0d229e818f8c7@git.kernel.org>
Date:	Thu, 18 Aug 2016 03:57:50 -0700
From:	tip-bot for Morten Rasmussen <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, hpa@...or.com, efault@....de,
	mingo@...nel.org, peterz@...radead.org, tglx@...utronix.de,
	morten.rasmussen@....com, linux-kernel@...r.kernel.org
Subject: [tip:sched/core] sched/core: Enable SD_BALANCE_WAKE for asymmetric
 capacity systems

Commit-ID:  9ee1cda5ee25c7dd82acf25892e0d229e818f8c7
Gitweb:     http://git.kernel.org/tip/9ee1cda5ee25c7dd82acf25892e0d229e818f8c7
Author:     Morten Rasmussen <morten.rasmussen@....com>
AuthorDate: Mon, 25 Jul 2016 14:34:24 +0100
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Thu, 18 Aug 2016 11:26:55 +0200

sched/core: Enable SD_BALANCE_WAKE for asymmetric capacity systems

A domain with the SD_ASYM_CPUCAPACITY flag set indicate that
sched_groups at this level and below do not include CPUs of all
capacities available (e.g. group containing little-only or big-only CPUs
in big.LITTLE systems). It is therefore necessary to put in more effort
in finding an appropriate CPU at task wake-up by enabling balancing at
wake-up (SD_BALANCE_WAKE) on all lower (child) levels.

Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Mike Galbraith <efault@....de>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: dietmar.eggemann@....com
Cc: freedom.tan@...iatek.com
Cc: keita.kobayashi.ym@...esas.com
Cc: mgalbraith@...e.de
Cc: sgurrappadi@...dia.com
Cc: vincent.guittot@...aro.org
Cc: yuyang.du@...el.com
Link: http://lkml.kernel.org/r/1469453670-2660-8-git-send-email-morten.rasmussen@arm.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 kernel/sched/core.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 5739465..4695df6 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6444,6 +6444,13 @@ sd_init(struct sched_domain_topology_level *tl,
 	 * Convert topological properties into behaviour.
 	 */
 
+	if (sd->flags & SD_ASYM_CPUCAPACITY) {
+		struct sched_domain *t = sd;
+
+		for_each_lower_domain(t)
+			t->flags |= SD_BALANCE_WAKE;
+	}
+
 	if (sd->flags & SD_SHARE_CPUCAPACITY) {
 		sd->flags |= SD_PREFER_SIBLING;
 		sd->imbalance_pct = 110;