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sched/fair: Implement ENQUEUE_DELAYED

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Doing a wakeup on a delayed dequeue task is about as simple as it
sounds -- remove the delayed mark and enjoy the fact it was actually
still on the runqueue.

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/20240727105029.888107381@infradead.org
This commit is contained in:
Peter Zijlstra 2024-05-23 11:57:43 +02:00
parent f12e148892
commit 781773e3b6
1 changed files with 31 additions and 2 deletions
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33
kernel/sched/fair.c
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@ -5289,6 +5289,9 @@ static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq);
static inline bool cfs_bandwidth_used(void);
static void
requeue_delayed_entity(struct sched_entity *se);
static void
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
{
@ -5922,8 +5925,10 @@ void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
for_each_sched_entity(se) {
struct cfs_rq *qcfs_rq = cfs_rq_of(se);
if (se->on_rq)
if (se->on_rq) {
SCHED_WARN_ON(se->sched_delayed);
break;
}
enqueue_entity(qcfs_rq, se, ENQUEUE_WAKEUP);
if (cfs_rq_is_idle(group_cfs_rq(se)))
@ -6773,6 +6778,22 @@ static int sched_idle_cpu(int cpu)
}
#endif
static void
requeue_delayed_entity(struct sched_entity *se)
{
struct cfs_rq *cfs_rq = cfs_rq_of(se);
/*
* se->sched_delayed should imply: se->on_rq == 1.
* Because a delayed entity is one that is still on
* the runqueue competing until elegibility.
*/
SCHED_WARN_ON(!se->sched_delayed);
SCHED_WARN_ON(!se->on_rq);
se->sched_delayed = 0;
}
/*
* The enqueue_task method is called before nr_running is
* increased. Here we update the fair scheduling stats and
@ -6787,6 +6808,11 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
int task_new = !(flags & ENQUEUE_WAKEUP);
int rq_h_nr_running = rq->cfs.h_nr_running;
if (flags & ENQUEUE_DELAYED) {
requeue_delayed_entity(se);
return;
}
/*
* The code below (indirectly) updates schedutil which looks at
* the cfs_rq utilization to select a frequency.
@ -6804,8 +6830,11 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
cpufreq_update_util(rq, SCHED_CPUFREQ_IOWAIT);
for_each_sched_entity(se) {
if (se->on_rq)
if (se->on_rq) {
if (se->sched_delayed)
requeue_delayed_entity(se);
break;
}
cfs_rq = cfs_rq_of(se);
enqueue_entity(cfs_rq, se, flags);