sched/core: Fix incorrect utilization accounting when switching to fair class (a399d233) · Commits · 戴 / test

When a task switches to fair scheduling class, the period between now and the last update of its utilization is accounted as running time whatever happened during this period. This incorrect accounting applies to the task and also to the task group branch. When changing the property of a running task like its list of allowed CPUs or its scheduling class, we follow the sequence: - dequeue task - put task - change the property - set task as current task - enqueue task The end of the sequence doesn't follow the normal sequence (as per __schedule()) which is: - enqueue a task - then set the task as current task. This incorrectordering is the root cause of incorrect utilization accounting. Update the sequence to follow the right one: - dequeue task - put task - change the property - enqueue task - set task as current task Signed-off-by:

Vincent Guittot <vincent.guittot@linaro.org> Signed-off-by:

Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Morten.Rasmussen@arm.com Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: bsegall@google.com Cc: dietmar.eggemann@arm.com Cc: linaro-kernel@lists.linaro.org Cc: pjt@google.com Cc: yuyang.du@intel.com Link: http://lkml.kernel.org/r/1473666472-13749-8-git-send-email-vincent.guittot@linaro.org Signed-off-by:

Ingo Molnar <mingo@kernel.org>

kernel/sched/core.c

+10 −10

Original line number	Diff line number	Diff line
		@@ -1109,10 +1109,10 @@ void do_set_cpus_allowed(struct task_struct p, const struct cpumask new_mask)

		p->sched_class->set_cpus_allowed(p, new_mask);

		if (running)
		p->sched_class->set_curr_task(rq);
		if (queued)
		enqueue_task(rq, p, ENQUEUE_RESTORE);
		if (running)
		p->sched_class->set_curr_task(rq);
		}

		/*
		@@ -3707,10 +3707,10 @@ void rt_mutex_setprio(struct task_struct *p, int prio)

		p->prio = prio;

		if (running)
		p->sched_class->set_curr_task(rq);
		if (queued)
		enqueue_task(rq, p, queue_flag);
		if (running)
		p->sched_class->set_curr_task(rq);

		check_class_changed(rq, p, prev_class, oldprio);
		out_unlock:
		@@ -4263,8 +4263,6 @@ change:
		prev_class = p->sched_class;
		__setscheduler(rq, p, attr, pi);

		if (running)
		p->sched_class->set_curr_task(rq);
		if (queued) {
		/*
		* We enqueue to tail when the priority of a task is
		@@ -4275,6 +4273,8 @@ change:

		enqueue_task(rq, p, queue_flags);
		}
		if (running)
		p->sched_class->set_curr_task(rq);

		check_class_changed(rq, p, prev_class, oldprio);
		preempt_disable(); /* avoid rq from going away on us */
		@@ -5439,10 +5439,10 @@ void sched_setnuma(struct task_struct *p, int nid)

		p->numa_preferred_nid = nid;

		if (running)
		p->sched_class->set_curr_task(rq);
		if (queued)
		enqueue_task(rq, p, ENQUEUE_RESTORE);
		if (running)
		p->sched_class->set_curr_task(rq);
		task_rq_unlock(rq, p, &rf);
		}
		#endif /* CONFIG_NUMA_BALANCING */
		@@ -7949,10 +7949,10 @@ void sched_move_task(struct task_struct *tsk)

		sched_change_group(tsk, TASK_MOVE_GROUP);

		if (unlikely(running))
		tsk->sched_class->set_curr_task(rq);
		if (queued)
		enqueue_task(rq, tsk, ENQUEUE_RESTORE \| ENQUEUE_MOVE);
		if (unlikely(running))
		tsk->sched_class->set_curr_task(rq);

		task_rq_unlock(rq, tsk, &rf);
		}

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