2024-01-24 17:09:46

by Frederic Weisbecker

Subject: [PATCH 10/15] tick: Assume the tick can't be stopped in NOHZ_MODE_INACTIVE mode

The full-nohz update function checks if the nohz mode is active before
proceeding. It considers one exception though: if the tick is already
stopped even though the nohz mode is inactive, it still moves on in
order to update/restart the tick if needed.

However in order for the tick to be stopped, the nohz_mode has to be
either NOHZ_MODE_LOWRES or NOHZ_MODE_HIGHRES. Therefore it doesn't make
sense to test if the tick is stopped before verifying NOHZ_MODE_INACTIVE
mode.

Remove the needless related condition.

Signed-off-by: Frederic Weisbecker <[email protected]>
---
kernel/time/tick-sched.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index e8e3b5d447e9..3104fff89007 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -1044,7 +1044,7 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts)
if (!tick_nohz_full_cpu(smp_processor_id()))
return;

- if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE)
+ if (ts->nohz_mode == NOHZ_MODE_INACTIVE)
return;

__tick_nohz_full_update_tick(ts, ktime_get());
--
2.43.0

2024-01-25 09:46:40

by Thomas Gleixner

Subject: Re: [PATCH 10/15] tick: Assume the tick can't be stopped in NOHZ_MODE_INACTIVE mode

On Wed, Jan 24 2024 at 18:04, Frederic Weisbecker wrote:
> The full-nohz update function checks if the nohz mode is active before
> proceeding. It considers one exception though: if the tick is already
> stopped even though the nohz mode is inactive, it still moves on in
> order to update/restart the tick if needed.
>
> However in order for the tick to be stopped, the nohz_mode has to be
> either NOHZ_MODE_LOWRES or NOHZ_MODE_HIGHRES. Therefore it doesn't make
> sense to test if the tick is stopped before verifying NOHZ_MODE_INACTIVE
> mode.
>
> Remove the needless related condition.
>
> Signed-off-by: Frederic Weisbecker <[email protected]>

Reviewed-by: Thomas Gleixner <[email protected]>