linux-kernel - [PATCH v2 05/13] sched: Enable SD_BALANCE

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Message-Id: <1466615004-3503-6-git-send-email-morten.rasmussen@arm.com>
Date:	Wed, 22 Jun 2016 18:03:16 +0100
From:	Morten Rasmussen <morten.rasmussen@....com>
To:	peterz@...radead.org, mingo@...hat.com
Cc:	dietmar.eggemann@....com, yuyang.du@...el.com,
	vincent.guittot@...aro.org, mgalbraith@...e.de,
	linux-kernel@...r.kernel.org,
	Morten Rasmussen <morten.rasmussen@....com>
Subject: [PATCH v2 05/13] sched: Enable SD_BALANCE_WAKE for asymmetric capacity systems

Systems with the SD_ASYM_CPUCAPACITY flag set indicate that sched_groups
at this level or 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).

cc: Ingo Molnar <mingo@...hat.com>
cc: Peter Zijlstra <peterz@...radead.org>

Signed-off-by: Morten Rasmussen <morten.rasmussen@....com>
---
 kernel/sched/core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/sched/core.c b/kernel/sched/core.c
index 351609279341..fe39118ffdfb 100644
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -6397,6 +6397,9 @@ sd_init(struct sched_domain_topology_level *tl, int cpu)
 	 * Convert topological properties into behaviour.
 	 */
 
+	if (sd->flags & SD_ASYM_CPUCAPACITY)
+		sd->flags |= SD_BALANCE_WAKE;
+
 	if (sd->flags & SD_SHARE_CPUCAPACITY) {
 		sd->flags |= SD_PREFER_SIBLING;
 		sd->imbalance_pct = 110;
-- 
1.9.1