Commit f4904815 authored Aug 02, 2019 by Dietmar Eggemann Committed by Peter Zijlstra Aug 06, 2019

sched/deadline: Fix double accounting of rq/running bw in push & pull



{push,pull}_dl_task() always calls {de,}activate_task() with .flags=0
which sets p->on_rq=TASK_ON_RQ_MIGRATING.

{push,pull}_dl_task()->{de,}activate_task()->{de,en}queue_task()->
{de,en}queue_task_dl() calls {sub,add}_{running,rq}_bw() since
p->on_rq==TASK_ON_RQ_MIGRATING.
So {sub,add}_{running,rq}_bw() in {push,pull}_dl_task() is
double-accounting for that task.

Fix it by removing rq/running bw accounting in [push/pull]_dl_task().

Fixes: 7dd77884 ("sched/core: Unify p->on_rq updates")
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Valentin Schneider <valentin.schneider@arm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Luca Abeni <luca.abeni@santannapisa.it>
Cc: Daniel Bristot de Oliveira <bristot@redhat.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Qais Yousef <qais.yousef@arm.com>
Link: https://lkml.kernel.org/r/20190802145945.18702-2-dietmar.eggemann@arm.com

parent e21a712a

kernel/sched/deadline.c

+0 −8

Original line number	Diff line number	Diff line
		@@ -2088,17 +2088,13 @@ retry:
		}

		deactivate_task(rq, next_task, 0);
		sub_running_bw(&next_task->dl, &rq->dl);
		sub_rq_bw(&next_task->dl, &rq->dl);
		set_task_cpu(next_task, later_rq->cpu);
		add_rq_bw(&next_task->dl, &later_rq->dl);

		/*
		* Update the later_rq clock here, because the clock is used
		* by the cpufreq_update_util() inside __add_running_bw().
		*/
		update_rq_clock(later_rq);
		add_running_bw(&next_task->dl, &later_rq->dl);
		activate_task(later_rq, next_task, ENQUEUE_NOCLOCK);
		ret = 1;

		@@ -2186,11 +2182,7 @@ static void pull_dl_task(struct rq *this_rq)
		resched = true;

		deactivate_task(src_rq, p, 0);
		sub_running_bw(&p->dl, &src_rq->dl);
		sub_rq_bw(&p->dl, &src_rq->dl);
		set_task_cpu(p, this_cpu);
		add_rq_bw(&p->dl, &this_rq->dl);
		add_running_bw(&p->dl, &this_rq->dl);
		activate_task(this_rq, p, 0);
		dmin = p->dl.deadline;

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