linux-kernel - [PATCH v3 2/6] sched: explicitly cpu_idle_type checking in rebalance

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Message-Id: <1366705662-3587-3-git-send-email-iamjoonsoo.kim@lge.com>
Date:	Tue, 23 Apr 2013 17:27:38 +0900
From:	Joonsoo Kim <iamjoonsoo.kim@....com>
To:	Ingo Molnar <mingo@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>
Cc:	linux-kernel@...r.kernel.org,
	Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>,
	Davidlohr Bueso <davidlohr.bueso@...com>,
	Jason Low <jason.low2@...com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH v3 2/6] sched: explicitly cpu_idle_type checking in rebalance_domains()

After commit 88b8dac0, dst-cpu can be changed in load_balance(),
then we can't know cpu_idle_type of dst-cpu when load_balance()
return positive. So, add explicit cpu_idle_type checking.

Cc: Srivatsa Vaddagiri <vatsa@...ux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Tested-by: Jason Low <jason.low2@...com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 25aaf93..726e129 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -5523,10 +5523,11 @@ static void rebalance_domains(int cpu, enum cpu_idle_type idle)
 		if (time_after_eq(jiffies, sd->last_balance + interval)) {
 			if (load_balance(cpu, rq, sd, idle, &balance)) {
 				/*
-				 * We've pulled tasks over so either we're no
-				 * longer idle.
+				 * The LBF_SOME_PINNED logic could have changed
+				 * env->dst_cpu, so we can't know our idle
+				 * state even if we migrated tasks. Update it.
 				 */
-				idle = CPU_NOT_IDLE;
+				idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
 			}
 			sd->last_balance = jiffies;
 		}
-- 
1.7.9.5

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