On Thu, Dec 17, 2020 at 02:51:58PM +0800, Yunfeng Ye wrote:
>
>
> On 2020/12/15 22:47, Frederic Weisbecker wrote:
> > 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.
> >
> So is it necessary to modify the comment "@idle_exittime: Time when the
> idle state was left" ?
>
> On the other hand, if the patch "nohz: Update tick instead of restarting tick
> in tick_nohz_idle_exit()"
> (https://www.spinics.net/lists/kernel/msg3747039.html ) applied,
> __tick_nohz_idle_restart_tick will not
> be called always, So is it put here also a better place?
Right but I need to re-order some code before. That's ok, I'll integrate this
patch inside the changes.
Thanks.
