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| author | Ingo Molnar <mingo@kernel.org> | 2014-08-26 21:32:41 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2014-08-26 21:32:41 +0200 |
| commit | 42594970022d223bf8f30d3aa22819e24779d6f6 (patch) | |
| tree | 6b55f82a1fb1bb5dbb5ff61f90c41f7caa6a1f9b /kernel | |
| parent | Linux 3.17-rc2 (diff) | |
| parent | nohz: Avoid tick's double reprogramming in highres mode (diff) | |
| download | linux-42594970022d223bf8f30d3aa22819e24779d6f6.tar.xz linux-42594970022d223bf8f30d3aa22819e24779d6f6.zip | |
Merge branch 'nohz/drop-double-write-v3' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/core
Pull nohz fixes from Frederic Weisbecker:
" The tick reschedules itself unconditionally. It's relevant in periodic
mode but not in dynticks mode where it results in spurious double clock
writes and even spurious periodic behaviour for low-res case.
This set fixes that:
* 1st patch removes low-res periodic tick rescheduling in nohz mode.
This fixes spurious periodic behaviour.
* 2nd patch does the same for high-res mode. Here there is no such
spurious periodic behaviour but it still spares a double clock write
in some cases. "
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/time/tick-sched.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 99aa6ee3908f..cc0a5b6f741b 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -968,6 +968,10 @@ static void tick_nohz_handler(struct clock_event_device *dev) tick_sched_do_timer(now); tick_sched_handle(ts, regs); + /* No need to reprogram if we are running tickless */ + if (unlikely(ts->tick_stopped)) + return; + while (tick_nohz_reprogram(ts, now)) { now = ktime_get(); tick_do_update_jiffies64(now); @@ -1095,6 +1099,10 @@ static enum hrtimer_restart tick_sched_timer(struct hrtimer *timer) if (regs) tick_sched_handle(ts, regs); + /* No need to reprogram if we are in idle or full dynticks mode */ + if (unlikely(ts->tick_stopped)) + return HRTIMER_NORESTART; + hrtimer_forward(timer, now, tick_period); return HRTIMER_RESTART; |