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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 <yeyunfeng@huawei.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20210512232924.150322-5-frederic@kernel.org
This commit is contained in:
Yunfeng Ye 2021-05-13 01:29:18 +02:00 committed by Ingo Molnar
parent 3f624314b3
commit 96c9b90396
1 changed files with 8 additions and 6 deletions
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14
kernel/time/tick-sched.c
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@ -921,8 +921,6 @@ 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);
}
@ -1194,10 +1192,13 @@ unsigned long tick_nohz_get_idle_calls(void)
return ts->idle_calls;
}
static void tick_nohz_account_idle_ticks(struct tick_sched *ts)
static void tick_nohz_account_idle_time(struct tick_sched *ts,
ktime_t now)
{
unsigned long ticks;
ts->idle_exittime = now;
if (vtime_accounting_enabled_this_cpu())
return;
/*
@ -1218,8 +1219,9 @@ void tick_nohz_idle_restart_tick(void)
struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
if (ts->tick_stopped) {
tick_nohz_restart_sched_tick(ts, ktime_get());
tick_nohz_account_idle_ticks(ts);
ktime_t now = ktime_get();
tick_nohz_restart_sched_tick(ts, now);
tick_nohz_account_idle_time(ts, now);
}
}
@ -1230,7 +1232,7 @@ static void tick_nohz_idle_update_tick(struct tick_sched *ts, ktime_t now)
else
tick_nohz_restart_sched_tick(ts, now);
tick_nohz_account_idle_ticks(ts);
tick_nohz_account_idle_time(ts, now);
}
/**