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>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
Signed-off-by: kdrag0n <dragon@khronodragon.com>
ktime_t now, expires;
int cpu = smp_processor_id();
- now = tick_nohz_start_idle(ts);
-
#ifdef CONFIG_SMP
if (check_pending_deferrable_timers(cpu))
raise_softirq_irqoff(TIMER_SOFTIRQ);
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);