On Tue, Dec 15, 2020 at 08:06:34PM +0800, Yunfeng Ye wrote:
> The idle_exittime field of tick_sched is used to record the time when
> the idle state was left. but currently the idle_exittime is updated in
> the function tick_nohz_restart_sched_tick(), which is not always in idle
> state when nohz_full is configured.
>
> tick_irq_exit
> tick_nohz_irq_exit
> tick_nohz_full_update_tick
> tick_nohz_restart_sched_tick
> ts->idle_exittime = now;
>
> So move to tick_nohz_stop_idle() to make the idle_exittime update
> correctly.
>
> Signed-off-by: Yunfeng Ye <yeyunf...@huawei.com>
> ---
> 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 749ec2a583de..be2e5d772d50 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -591,6 +591,7 @@ static void tick_nohz_stop_idle(struct tick_sched *ts,
> ktime_t now)
> {
> update_ts_time_stats(smp_processor_id(), ts, now, NULL);
> ts->idle_active = 0;
> + ts->idle_exittime = now;
This changes a bit the meaning of idle_exittime then since this is also called
from idle interrupt entry.
__tick_nohz_idle_restart_tick() would be a better place.
Thanks.
>
> sched_clock_idle_wakeup_event();
> }
> @@ -901,7 +902,6 @@ static void tick_nohz_restart_sched_tick(struct
> tick_sched *ts, ktime_t now)
> * Cancel the scheduled timer and restore the tick
> */
> ts->tick_stopped = 0;
> - ts->idle_exittime = now;
>
> tick_nohz_restart(ts, now);
> }
> --
> 2.18.4
>
