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sched/fair: Prepare pick_next_task() for delayed dequeue

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Delayed dequeue's natural end is when it gets picked again. Ensure
pick_next_task() knows what to do with delayed tasks.

Note, this relies on the earlier patch that made pick_next_task()
state invariant -- it will restart the pick on dequeue, because
obviously the just dequeued task is no longer eligible.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lkml.kernel.org/r/20240727105029.747330118@infradead.org
This commit is contained in:
Peter Zijlstra 2024-05-23 11:26:25 +02:00
parent 2e0199df25
commit f12e148892
1 changed files with 19 additions and 4 deletions
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23
kernel/sched/fair.c
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@ -5473,6 +5473,8 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
se->prev_sum_exec_runtime = se->sum_exec_runtime; se->prev_sum_exec_runtime = se->sum_exec_runtime;
} }
static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags);
/* /*
* Pick the next process, keeping these things in mind, in this order: * Pick the next process, keeping these things in mind, in this order:
* 1) keep things fair between processes/task groups * 1) keep things fair between processes/task groups
@ -5481,16 +5483,27 @@ set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
* 4) do not run the "skip" process, if something else is available * 4) do not run the "skip" process, if something else is available
*/ */
static struct sched_entity * static struct sched_entity *
pick_next_entity(struct cfs_rq *cfs_rq) pick_next_entity(struct rq *rq, struct cfs_rq *cfs_rq)
{ {
/* /*
* Enabling NEXT_BUDDY will affect latency but not fairness. * Enabling NEXT_BUDDY will affect latency but not fairness.
*/ */
if (sched_feat(NEXT_BUDDY) && if (sched_feat(NEXT_BUDDY) &&
cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next)) cfs_rq->next && entity_eligible(cfs_rq, cfs_rq->next)) {
/* ->next will never be delayed */
SCHED_WARN_ON(cfs_rq->next->sched_delayed);
return cfs_rq->next; return cfs_rq->next;
}
return pick_eevdf(cfs_rq); struct sched_entity *se = pick_eevdf(cfs_rq);
if (se->sched_delayed) {
dequeue_entities(rq, se, DEQUEUE_SLEEP | DEQUEUE_DELAYED);
SCHED_WARN_ON(se->sched_delayed);
SCHED_WARN_ON(se->on_rq);
return NULL;
}
return se;
} }
static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq); static bool check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
@ -8507,7 +8520,9 @@ static struct task_struct *pick_task_fair(struct rq *rq)
if (unlikely(check_cfs_rq_runtime(cfs_rq))) if (unlikely(check_cfs_rq_runtime(cfs_rq)))
goto again; goto again;
se = pick_next_entity(cfs_rq); se = pick_next_entity(rq, cfs_rq);
if (!se)
goto again;
cfs_rq = group_cfs_rq(se); cfs_rq = group_cfs_rq(se);
} while (cfs_rq); } while (cfs_rq);