On Sat, Dec 05, 2020 at 05:41:52PM +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; > > 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); > }
Hi, I've edited and queued on top of latest changes, see below. I'll post it after the merge window. --- From: Yunfeng Ye <yeyunf...@huawei.com> Date: Wed, 10 Feb 2021 00:08:54 +0100 Subject: [PATCH] tick/nohz: Update idle_exittime on actual idle exit 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; It's thus overwritten by mistake on nohz_full tick restart. Move the update to the appropriate idle exit path instead. Signed-off-by: Yunfeng Ye <yeyunf...@huawei.com> Signed-off-by: Frederic Weisbecker <frede...@kernel.org> --- kernel/time/tick-sched.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 79796286a4ba..2907c762a8fe 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -918,8 +918,6 @@ 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); } @@ -1231,6 +1229,7 @@ static void tick_nohz_idle_update_tick(struct tick_sched *ts, ktime_t now) else tick_nohz_restart_sched_tick(ts, now); + ts->idle_exittime = now; tick_nohz_account_idle_ticks(ts); } -- 2.25.1