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Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull NOHZ fix from Ingo Molnar:
 "This fixes an old NOHZ race where we incorrectly calculate the next
  timer interrupt in certain circumstances where hrtimers are pending,
  that can cause hard to reproduce stalled-values artifacts in
  /proc/stat"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  nohz: Fix collision between tick and other hrtimers
This commit is contained in:
Linus Torvalds 2017-01-15 12:00:37 -08:00
parent 79078c53ba 24b91e360e
commit a11ce3a4ac
2 changed files with 9 additions and 2 deletions
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9
kernel/time/tick-sched.c
View File

@ -767,7 +767,7 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
tick = expires;
/* Skip reprogram of event if its not changed */
if (ts->tick_stopped && (expires == dev->next_event))
if (ts->tick_stopped && (expires == ts->next_tick))
goto out;
/*
@ -787,6 +787,8 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
trace_tick_stop(1, TICK_DEP_MASK_NONE);
}
ts->next_tick = tick;
/*
* If the expiration time == KTIME_MAX, then we simply stop
* the tick timer.
@ -802,7 +804,10 @@ static ktime_t tick_nohz_stop_sched_tick(struct tick_sched *ts,
else
tick_program_event(tick, 1);
out:
/* Update the estimated sleep length */
/*
* Update the estimated sleep length until the next timer
* (not only the tick).
*/
ts->sleep_length = ktime_sub(dev->next_event, now);
return tick;
}

2
kernel/time/tick-sched.h
View File

@ -27,6 +27,7 @@ enum tick_nohz_mode {
* timer is modified for nohz sleeps. This is necessary
* to resume the tick timer operation in the timeline
* when the CPU returns from nohz sleep.
* @next_tick: Next tick to be fired when in dynticks mode.
* @tick_stopped: Indicator that the idle tick has been stopped
* @idle_jiffies: jiffies at the entry to idle for idle time accounting
* @idle_calls: Total number of idle calls
@ -44,6 +45,7 @@ struct tick_sched {
unsigned long check_clocks;
enum tick_nohz_mode nohz_mode;
ktime_t last_tick;
ktime_t next_tick;
int inidle;
int tick_stopped;
unsigned long idle_jiffies;