Commit-ID: 2a16fc93d2c9568e16d45db77c7b5f15e1921cf1 Gitweb: http://git.kernel.org/tip/2a16fc93d2c9568e16d45db77c7b5f15e1921cf1 Author: Viresh Kumar <viresh.kumar@xxxxxxxxxx> AuthorDate: Thu, 12 Jun 2014 16:24:41 +0530 Committer: Frederic Weisbecker <frederic@xxxxxxxxxx> CommitDate: Fri, 22 Aug 2014 18:47:35 +0200 nohz: Avoid tick's double reprogramming in highres mode In highres mode, the tick reschedules itself unconditionally to the next jiffies. However while this clock reprogramming is relevant when the tick is in periodic mode, it's not that interesting when we run in dynticks mode because irq exit is likely going to overwrite the next tick to some randomly deferred future. So lets just get rid of this tick self rescheduling in dynticks mode. This way we can avoid some clockevents double write in favourable scenarios like when we stop the tick completely in idle while no other hrtimer is pending. Suggested-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx> --- kernel/time/tick-sched.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 153870a..cc0a5b6 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -1099,6 +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; -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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