Commit cea5a347 authored by Peter Zijlstra's avatar Peter Zijlstra
Browse files

sched/fair: Cleanup fair_server 



The throttle interaction made my brain hurt, make it consistently
about 0 transitions of h_nr_running.

Signed-off-by: default avatarPeter Zijlstra (Intel) <peterz@infradead.org>
parent 5f6bd380

kernel/sched/fair.c

+17 −15
Original line number Diff line number Diff line
@@ -5849,10 +5849,10 @@ static bool throttle_cfs_rq(struct cfs_rq *cfs_rq) 
	/* At this point se is NULL and we are at root level*/

	sub_nr_running(rq, task_delta);



done:

	/* Stop the fair server if throttling resulted in no runnable tasks */

	if (rq_h_nr_running && !rq->cfs.h_nr_running)

		dl_server_stop(&rq->fair_server);

done:

	/*

	 * Note: distribution will already see us throttled via the

	 * throttled-list.  rq->lock protects completion.
@@ -5940,16 +5940,16 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq) 
			goto unthrottle_throttle;

	}



	/* Start the fair server if un-throttling resulted in new runnable tasks */

	if (!rq_h_nr_running && rq->cfs.h_nr_running)

		dl_server_start(&rq->fair_server);



	/* At this point se is NULL and we are at root level*/

	add_nr_running(rq, task_delta);



unthrottle_throttle:

	assert_list_leaf_cfs_rq(rq);



	/* Start the fair server if un-throttling resulted in new runnable tasks */

	if (!rq_h_nr_running && rq->cfs.h_nr_running)

		dl_server_start(&rq->fair_server);



	/* Determine whether we need to wake up potentially idle CPU: */

	if (rq->curr == rq->idle && rq->cfs.nr_running)

		resched_curr(rq);
@@ -6771,6 +6771,7 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	struct sched_entity *se = &p->se;

	int idle_h_nr_running = task_has_idle_policy(p);

	int task_new = !(flags & ENQUEUE_WAKEUP);

	int rq_h_nr_running = rq->cfs.h_nr_running;



	/*

	 * The code below (indirectly) updates schedutil which looks at
@@ -6780,13 +6781,6 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	 */

	util_est_enqueue(&rq->cfs, p);



	if (!throttled_hierarchy(task_cfs_rq(p)) && !rq->cfs.h_nr_running) {

		/* Account for idle runtime */

		if (!rq->nr_running)

			dl_server_update_idle_time(rq, rq->curr);

		dl_server_start(&rq->fair_server);

	}



	/*

	 * If in_iowait is set, the code below may not trigger any cpufreq

	 * utilization updates, so do it here explicitly with the IOWAIT flag
@@ -6832,6 +6826,13 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
			goto enqueue_throttle;

	}



	if (!rq_h_nr_running && rq->cfs.h_nr_running) {

		/* Account for idle runtime */

		if (!rq->nr_running)

			dl_server_update_idle_time(rq, rq->curr);

		dl_server_start(&rq->fair_server);

	}



	/* At this point se is NULL and we are at root level*/

	add_nr_running(rq, 1);
@@ -6872,6 +6873,7 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	int task_sleep = flags & DEQUEUE_SLEEP;

	int idle_h_nr_running = task_has_idle_policy(p);

	bool was_sched_idle = sched_idle_rq(rq);

	int rq_h_nr_running = rq->cfs.h_nr_running;



	util_est_dequeue(&rq->cfs, p);
@@ -6926,14 +6928,14 @@ static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags) 
	/* At this point se is NULL and we are at root level*/

	sub_nr_running(rq, 1);



	if (rq_h_nr_running && !rq->cfs.h_nr_running)

		dl_server_stop(&rq->fair_server);



	/* balance early to pull high priority tasks */

	if (unlikely(!was_sched_idle && sched_idle_rq(rq)))

		rq->next_balance = jiffies;



dequeue_throttle:

	if (!throttled_hierarchy(task_cfs_rq(p)) && !rq->cfs.h_nr_running)

		dl_server_stop(&rq->fair_server);



	util_est_update(&rq->cfs, p, task_sleep);

	hrtick_update(rq);

}