[tip:sched/core] sched/fair: Remove task and group entity load when they are dead

[tip-bot for Yuyang Du]

Commit-ID:  1269557889b477e3e43ab99a21035ddf8f7cea4d
Gitweb:     http://git.kernel.org/tip/1269557889b477e3e43ab99a21035ddf8f7cea4d
Author:     Yuyang Du <yuyang.du@xxxxxxxxx>
AuthorDate: Wed, 15 Jul 2015 08:04:40 +0800
Committer:  Ingo Molnar <mingo@xxxxxxxxxx>
CommitDate: Mon, 3 Aug 2015 12:24:30 +0200

sched/fair: 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@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: arjan@xxxxxxxxxxxxxxx
Cc: bsegall@xxxxxxxxxx
Cc: dietmar.eggemann@xxxxxxx
Cc: fengguang.wu@xxxxxxxxx
Cc: len.brown@xxxxxxxxx
Cc: morten.rasmussen@xxxxxxx
Cc: pjt@xxxxxxxxxx
Cc: rafael.j.wysocki@xxxxxxxxx
Cc: umgwanakikbuti@xxxxxxxxx
Cc: vincent.guittot@xxxxxxxxxx
Link: http://lkml.kernel.org/r/1436918682-4971-6-git-send-email-yuyang.du@xxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
---
 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 f636db0..5532bf3 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4913,6 +4913,11 @@ 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
@@ -7991,8 +7996,11 @@ 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);
@@ -8179,6 +8187,7 @@ 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,
--
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