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authorLinus Torvalds <torvalds@linux-foundation.org>2017-01-15 12:00:37 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2017-01-15 12:00:37 -0800
commita11ce3a4ac0ad78618cddb9ce16def7486f2707d (patch)
tree96f6f9b7f979dcfa94d036d7431fdd799b108638 /kernel
parent79078c53baabee12dfefb0cfe00ca94cb2c35570 (diff)
parent24b91e360ef521a2808771633d76ebc68bd5604b (diff)
downloadlinux-a11ce3a4ac0ad78618cddb9ce16def7486f2707d.tar.bz2
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
Diffstat (limited to 'kernel')
-rw-r--r--kernel/time/tick-sched.c9
-rw-r--r--kernel/time/tick-sched.h2
2 files changed, 9 insertions, 2 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
index 2c115fdab397..74e0388cc88d 100644
--- a/kernel/time/tick-sched.c
+++ b/kernel/time/tick-sched.c
@@ -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;
}
diff --git a/kernel/time/tick-sched.h b/kernel/time/tick-sched.h
index bf38226e5c17..075444e3d48e 100644
--- a/kernel/time/tick-sched.h
+++ b/kernel/time/tick-sched.h
@@ -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;