Re: [PATCH V3 2/2] sched: idle: IRQ based next prediction for idle period

[Daniel Lezcano]

On 02/22/2016 04:02 PM, Shreyas B Prabhu wrote:
> Hi Daniel,
>
> On 02/16/2016 09:13 PM, Daniel Lezcano wrote:
> > +
> > +/**
> > + * sched_idle_next_wakeup - Predict the next wakeup on the current cpu
> > + *
> > + * The next event on the cpu is based on a statistic approach of the
> > + * interrupt events and the timer deterministic value. From the timer
> > + * or the irqs, we return the one expected to occur first.
> > + *
> > + * Returns the expected remaining idle time before being woken up by
> > + * an interruption.
> > + */
> > +s64 sched_idle_next_wakeup(void)
> > +{
> > +	s64 next_timer = ktime_to_us(tick_nohz_get_sleep_length());
> > +	s64 next_irq = next_irq_event();
>
> Since next_irq_event() uses RCU and we are in idle this should probably
> be wrapped in RCU_NONIDLE().

That is a good point but the function is not supposed to be called in 
the rcu_idle_enter/rcu_idle_exit section which is inside 
cpuidle_idle_call().


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