linux-kernel - [PATCH 2/2] sched: load_balance: Reset env when going to redo due to all pinned

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Date:	Sun, 15 Sep 2013 21:30:14 +0400
From:	Vladimir Davydov <vdavydov@...allels.com>
To:	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>
CC:	Paul Turner <pjt@...gle.com>, <linux-kernel@...r.kernel.org>,
	<devel@...nvz.org>
Subject: [PATCH 2/2] sched: load_balance: Reset env when going to redo due to all pinned

Firstly, reset env.dst_cpu/dst_rq to this_cpu/this_rq, because it could
have changed in 'some pinned' case. Otherwise, should_we_balance() can
stop balancing beforehand.

Secondly, reset env.flags, because it can have LBF_SOME_PINNED set.

Thirdly, reset env.dst_grpmask cpus in env.cpus to allow handling 'some
pinned' case when pulling tasks from a new busiest cpu.

Signed-off-by: Vladimir Davydov <vdavydov@...allels.com>
---
 kernel/sched/fair.c |   12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index cd59640..d840e51 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5289,8 +5289,16 @@ more_balance:
 		if (unlikely(env.flags & LBF_ALL_PINNED)) {
 			cpumask_clear_cpu(cpu_of(busiest), cpus);
 			if (!cpumask_empty(cpus)) {
-				env.loop = 0;
-				env.loop_break = sched_nr_migrate_break;
+				env.dst_cpu	= this_cpu;
+				env.dst_rq	= this_rq;
+				env.flags	= 0;
+				env.loop	= 0;
+				env.loop_break	= sched_nr_migrate_break;
+
+				/* Reset cpus cleared in LBF_SOME_PINNED case */
+				if (env.dst_grpmask)
+					cpumask_or(cpus, cpus, env.dst_grpmask);
+
 				goto redo;
 			}
 			goto out_balanced;
-- 
1.7.10.4

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