[tip: sched/core] kernel/sched: Fix util_est accounting for DELAY_DEQUEUE

tip-bot2 for Dietmar Eggemann
2024-09-10T08:09:32Z

The following commit has been merged into the sched/core branch of tip:

Commit-ID: 729288bc68560b4d5b094cb7a6f794c752ef22a2
Gitweb: https://git.kernel.org/tip/729288bc68560b4d5b094cb7a6f794c752ef22a2
Author: Dietmar Eggemann <dietmar.eggemann@arm.com>
AuthorDate: Thu, 05 Sep 2024 00:05:23 +02:00
Committer: Peter Zijlstra <peterz@infradead.org>
CommitterDate: Tue, 10 Sep 2024 09:51:15 +02:00

kernel/sched: Fix util_est accounting for DELAY_DEQUEUE

Remove delayed tasks from util_est even they are runnable.

Exclude delayed task which are (a) migrating between rq's or (b) in a
SAVE/RESTORE dequeue/enqueue.

Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/c49ef5fe-a909-43f1-b02f-a765ab9cedbf@arm.com
---
kernel/sched/fair.c | 16 +++++++++-------
1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index e946ca0..922d690 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -6948,18 +6948,19 @@ enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
int rq_h_nr_running = rq->cfs.h_nr_running;
u64 slice = 0;

- 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.
* Let's add the task's estimated utilization to the cfs_rq's
* estimated utilization, before we update schedutil.
*/
- util_est_enqueue(&rq->cfs, p);
+ if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & ENQUEUE_RESTORE))))
+ util_est_enqueue(&rq->cfs, p);
+
+ if (flags & ENQUEUE_DELAYED) {
+ requeue_delayed_entity(se);
+ return;
+ }

/*
* If in_iowait is set, the code below may not trigger any cpufreq
@@ -7177,7 +7178,8 @@ static int dequeue_entities(struct rq *rq, struct sched_entity *se, int flags)
*/
static bool dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
{
- util_est_dequeue(&rq->cfs, p);
+ if (!(p->se.sched_delayed && (task_on_rq_migrating(p) || (flags & DEQUEUE_SAVE))))
+ util_est_dequeue(&rq->cfs, p);

if (dequeue_entities(rq, &p->se, flags) < 0) {
util_est_update(&rq->cfs, p, DEQUEUE_SLEEP);