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Commit c18a1732 authored by Ingo Molnar's avatar Ingo Molnar
Browse files

sched: remove expired_starving() 



remove the expired_starving() heuristics from the core scheduler.

CFS does not need it, and this did not really work well in practice
anyway, due to the rq->nr_running multiplier to STARVATION_LIMIT.

Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent f2ac58ee

kernel/sched.c

+1 −22
Original line number Diff line number Diff line
@@ -3240,27 +3240,6 @@ unsigned long long task_sched_runtime(struct task_struct *p) 
	return ns;

}



/*

 * We place interactive tasks back into the active array, if possible.

 *

 * To guarantee that this does not starve expired tasks we ignore the

 * interactivity of a task if the first expired task had to wait more

 * than a 'reasonable' amount of time. This deadline timeout is

 * load-dependent, as the frequency of array switched decreases with

 * increasing number of running tasks. We also ignore the interactivity

 * if a better static_prio task has expired:

 */

static inline int expired_starving(struct rq *rq)

{

	if (rq->curr->static_prio > rq->best_expired_prio)

		return 1;

	if (!STARVATION_LIMIT || !rq->expired_timestamp)

		return 0;

	if (jiffies - rq->expired_timestamp > STARVATION_LIMIT * rq->nr_running)

		return 1;

	return 0;

}



/*

 * Account user cpu time to a process.

 * @p: the process that the cpu time gets accounted to
@@ -3373,7 +3352,7 @@ static void task_running_tick(struct rq *rq, struct task_struct *p) 


		if (!rq->expired_timestamp)

			rq->expired_timestamp = jiffies;

		if (!TASK_INTERACTIVE(p) || expired_starving(rq)) {

		if (!TASK_INTERACTIVE(p)) {

			enqueue_task(p, rq->expired);

			if (p->static_prio < rq->best_expired_prio)

				rq->best_expired_prio = p->static_prio;