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Commit 8663e24d authored by Peter Zijlstra's avatar Peter Zijlstra Committed by Ingo Molnar
Browse files

sched/fair: Reorder cgroup creation code 



A future patch needs rq->lock held _after_ we link the task_group into
the hierarchy. In order to avoid taking every rq->lock twice, reorder
things a little and create online_fair_sched_group() to be called
after we link the task_group.

All this code is still ran from css_alloc() so css_online() isn't in
fact used for this.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: bsegall@google.com
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 3d30544f

kernel/sched/core.c

+2 −0
Original line number Diff line number Diff line
@@ -7717,6 +7717,8 @@ void sched_online_group(struct task_group *tg, struct task_group *parent) 
	INIT_LIST_HEAD(&tg->children);

	list_add_rcu(&tg->siblings, &parent->children);

	spin_unlock_irqrestore(&task_group_lock, flags);



	online_fair_sched_group(tg);

}



/* rcu callback to free various structures associated with a task group */

kernel/sched/fair.c

+18 −4
Original line number Diff line number Diff line
@@ -8624,10 +8624,6 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) 
		init_cfs_rq(cfs_rq);

		init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);

		init_entity_runnable_average(se);



		raw_spin_lock_irq(&rq->lock);

		post_init_entity_util_avg(se);

		raw_spin_unlock_irq(&rq->lock);

	}



	return 1;
@@ -8638,6 +8634,22 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) 
	return 0;

}



void online_fair_sched_group(struct task_group *tg)

{

	struct sched_entity *se;

	struct rq *rq;

	int i;



	for_each_possible_cpu(i) {

		rq = cpu_rq(i);

		se = tg->se[i];



		raw_spin_lock_irq(&rq->lock);

		post_init_entity_util_avg(se);

		raw_spin_unlock_irq(&rq->lock);

	}

}



void unregister_fair_sched_group(struct task_group *tg)

{

	unsigned long flags;
@@ -8742,6 +8754,8 @@ int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent) 
	return 1;

}



void online_fair_sched_group(struct task_group *tg) { }



void unregister_fair_sched_group(struct task_group *tg) { }



#endif /* CONFIG_FAIR_GROUP_SCHED */

kernel/sched/sched.h

+1 −0
Original line number Diff line number Diff line
@@ -321,6 +321,7 @@ extern int tg_nop(struct task_group *tg, void *data); 


extern void free_fair_sched_group(struct task_group *tg);

extern int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent);

extern void online_fair_sched_group(struct task_group *tg);

extern void unregister_fair_sched_group(struct task_group *tg);

extern void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,

			struct sched_entity *se, int cpu,