sched: Ensure a task has a non-normalized vruntime when returning back to CFS (7855a35a) · Commits · 戴 / test

Current code ensures that a task has a normalized vruntime when switching away from the fair class, but it does not ensure the task has a non-normalized vruntime when switching back to the fair class. This is an example breaking this consistency: 1. a task is in fair class and !queued 2. changes its class to RT class (still !queued) 3. changes its class to fair class again (still !queued) Signed-off-by:

Byungchul Park <byungchul.park@lge.com> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> 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> Link: http://lkml.kernel.org/r/1439197375-27927-1-git-send-email-byungchul.park@lge.com Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/fair.c

+17 −2

Original line number	Diff line number	Diff line
		@@ -7930,16 +7930,31 @@ static void switched_from_fair(struct rq rq, struct task_struct p)
		*/
		static void switched_to_fair(struct rq rq, struct task_struct p)
		{
		#ifdef CONFIG_FAIR_GROUP_SCHED
		struct sched_entity *se = &p->se;

		#ifdef CONFIG_FAIR_GROUP_SCHED
		/*
		* Since the real-depth could have been changed (only FAIR
		* class maintain depth value), reset depth properly.
		*/
		se->depth = se->parent ? se->parent->depth + 1 : 0;
		#endif
		if (!task_on_rq_queued(p))

		if (!task_on_rq_queued(p)) {

		/*
		* Ensure the task has a non-normalized vruntime when it is switched
		* back to the fair class with !queued, so that enqueue_entity() at
		* wake-up time will do the right thing.
		*
		* If it's queued, then the enqueue_entity(.flags=0) makes the task
		* has non-normalized vruntime, if it's !queued, then it still has
		* normalized vruntime.
		*/
		if (p->state != TASK_RUNNING)
		se->vruntime += cfs_rq_of(se)->min_vruntime;
		return;
		}

		/*
		* We were most likely switched from sched_rt, so

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