diff options
| author | Gaurav Jindal <Gaurav.Jindal@spreadtrum.com> | 2016-07-14 12:04:20 (GMT) |
|---|---|---|
| committer | Thomas Gleixner <tglx@linutronix.de> | 2016-07-19 11:48:24 (GMT) |
| commit | 1f3b0f8243cb934307f59bd4d8e43b868e61d4d9 (patch) | |
| tree | d90d8e192e06c3f7de17bfb7e74a32269b05c910 | |
| parent | 775be506266a860f141f6b848c92c316c602a94f (diff) | |
| download | linux-1f3b0f8243cb934307f59bd4d8e43b868e61d4d9.tar.xz | |
tick/nohz: Optimize nohz idle enter
tick_nohz_start_idle is called before checking whether the idle tick can be
stopped. If the tick cannot be stopped, calling tick_nohz_start_idle() is
pointless and just wasting CPU cycles.
Only invoke tick_nohz_start_idle() when can_stop_idle_tick() returns true. A
short one minute observation of the effect on ARM64 shows a reduction of calls
by 1.5% thus optimizing the idle entry sequence.
[tglx: Massaged changelog ]
Co-developed-by: Sanjeev Yadav<sanjeev.yadav@spreadtrum.com>
Signed-off-by: Gaurav Jindal<gaurav.jindal@spreadtrum.com>
Link: http://lkml.kernel.org/r/20160714120416.GB21099@gaurav.jindal@spreadtrum.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
| -rw-r--r-- | kernel/time/tick-sched.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 2ec7c00..204fdc8 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -908,11 +908,10 @@ static void __tick_nohz_idle_enter(struct tick_sched *ts) ktime_t now, expires; int cpu = smp_processor_id(); - now = tick_nohz_start_idle(ts); - if (can_stop_idle_tick(cpu, ts)) { int was_stopped = ts->tick_stopped; + now = tick_nohz_start_idle(ts); ts->idle_calls++; expires = tick_nohz_stop_sched_tick(ts, now, cpu); |