Messages in this thread | | | Date | Fri, 11 Apr 2014 15:34:23 +0530 | Subject | Re: [Query]: tick-sched: why don't we stop tick when we are running idle task? | From | Viresh Kumar <> |
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On 10 April 2014 20:09, Frederic Weisbecker <fweisbec@gmail.com> wrote: > diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c > index 9f8af69..1e2d6b7 100644 > --- a/kernel/time/tick-sched.c > +++ b/kernel/time/tick-sched.c > @@ -202,13 +202,16 @@ static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now); > void __tick_nohz_full_check(void) > { > struct tick_sched *ts = &__get_cpu_var(tick_cpu_sched); > + unsigned long flags; > > + local_irq_save(flags);
As we need to disable interrupts to read this variable, would it be better to just remove this completely and use is_idle_task(current) instead?
> if (tick_nohz_full_cpu(smp_processor_id())) { > - if (ts->tick_stopped && !is_idle_task(current)) { > + if (ts->tick_stopped && !ts->inidle)) { > if (!can_stop_full_tick()) > tick_nohz_restart_sched_tick(ts, ktime_get()); > } > } > + local_irq_restore(flags); > }
> If you like it I'll push it to Ingo.
Yes please. And thanks for the explanations. It was pretty useful.
I am looking to offload 1 second tick to timekeeping CPUs and so going through these frameworks. I don't have a working solution yet (even partially :)). Would send a RFC to you as soon as I get anything working.
-- viresh
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