linux-kernel - [PATCH v8 4/4] sched: Remove task and group entity load when they are dead

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Date:	Tue, 16 Jun 2015 03:26:07 +0800
From:	Yuyang Du <yuyang.du@...el.com>
To:	mingo@...nel.org, peterz@...radead.org,
	linux-kernel@...r.kernel.org
Cc:	pjt@...gle.com, bsegall@...gle.com, morten.rasmussen@....com,
	vincent.guittot@...aro.org, dietmar.eggemann@....com,
	arjan.van.de.ven@...el.com, len.brown@...el.com,
	rafael.j.wysocki@...el.com, fengguang.wu@...el.com,
	boqun.feng@...il.com, srikar@...ux.vnet.ibm.com,
	Yuyang Du <yuyang.du@...el.com>
Subject: [PATCH v8 4/4] sched: Remove task and group entity load when they are dead

When task exits or group is destroyed, the entity's load should be
removed from its parent cfs_rq's load. Otherwise, it will take time
for the parent cfs_rq to decay the dead entity's load to 0, which
is not desired.

Signed-off-by: Yuyang Du <yuyang.du@...el.com>
---
 kernel/sched/fair.c |   11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 08ab789..a8fd7b9 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4904,6 +4904,11 @@ static void migrate_task_rq_fair(struct task_struct *p, int next_cpu)
 	/* We have migrated, no longer consider this task hot */
 	p->se.exec_start = 0;
 }
+
+static void task_dead_fair(struct task_struct *p)
+{
+	remove_entity_load_avg(&p->se);
+}
 #endif /* CONFIG_SMP */
 
 static unsigned long
@@ -7998,8 +8003,11 @@ void free_fair_sched_group(struct task_group *tg)
 	for_each_possible_cpu(i) {
 		if (tg->cfs_rq)
 			kfree(tg->cfs_rq[i]);
-		if (tg->se)
+		if (tg->se) {
+			if (tg->se[i])
+				remove_entity_load_avg(tg->se[i]);
 			kfree(tg->se[i]);
+		}
 	}
 
 	kfree(tg->cfs_rq);
@@ -8186,6 +8194,7 @@ const struct sched_class fair_sched_class = {
 	.rq_offline		= rq_offline_fair,
 
 	.task_waking		= task_waking_fair,
+	.task_dead			= task_dead_fair,
 #endif
 
 	.set_curr_task          = set_curr_task_fair,
-- 
1.7.9.5

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