[v1] sched/fair: avoid redundant hrtimer check

[PATCH] sched/fair: avoid redundant hrtimer check

Posted by Huichun Feng 3 years, 10 months ago

The check is required iff HRTICK is enabled and DOUBLE_TICK is disabled,
avoid the redundant check by adding corresponding sched_feat() .

Signed-off-by: Huichun Feng <foxhoundsk.tw@gmail.com>
---
 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 77b2048a9..80cc1a924 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4668,7 +4668,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
 	/*
 	 * don't let the period tick interfere with the hrtick preemption
 	 */
-	if (!sched_feat(DOUBLE_TICK) &&
+	if (sched_feat(HRTICK) && !sched_feat(DOUBLE_TICK) &&
 			hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
 		return;
 #endif
-- 
2.36.1

Re: [PATCH] sched/fair: avoid redundant hrtimer check

Posted by Peter Zijlstra 3 years, 10 months ago

On Mon, Jun 06, 2022 at 08:26:12PM +0800, Huichun Feng wrote:
> The check is required iff HRTICK is enabled and DOUBLE_TICK is disabled,
> avoid the redundant check by adding corresponding sched_feat() .

How about: 'don't do that then'?

Re: [PATCH v2] sched/fair: avoid redundant hrtimer check

Posted by Huichun Feng 3 years, 10 months ago

The check is required iff HRTICK is enabled and DOUBLE_TICK is disabled,
don't do that then.

Signed-off-by: Huichun Feng <foxhoundsk.tw@gmail.com>
---

Changes since v1:
- Refine commit message

 kernel/sched/fair.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 77b2048a9..80cc1a924 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -4668,7 +4668,7 @@ entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
        /*
         * don't let the period tick interfere with the hrtick preemption
         */
-       if (!sched_feat(DOUBLE_TICK) &&
+       if (sched_feat(HRTICK) && !sched_feat(DOUBLE_TICK) &&
                        hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
                return;
 #endif
-- 
2.36.1

Re: [PATCH] sched/fair: avoid redundant hrtimer check

Posted by Huichun Feng 3 years, 10 months ago

Peter Zijlstra <peterz@infradead.org> 於 2022年6月9日 週四 下午8:29寫道：
>
> On Mon, Jun 06, 2022 at 08:26:12PM +0800, Huichun Feng wrote:
> > The check is required iff HRTICK is enabled and DOUBLE_TICK is disabled,
> > avoid the redundant check by adding corresponding sched_feat() .
>
> How about: 'don't do that then'?

Looks good!

Should I send a v2 for this? Or could you help amend it directly?

Thank you!
Huichun