Re: [PATCH V3 3/6] sched: idle: Get the next timer event and pass it the cpuidle framework

Peter Zijlstra
2014-11-10T12:44:08Z

On Fri, Nov 07, 2014 at 03:31:24PM +0100, Daniel Lezcano wrote:
> static void cpu_idle_loop(void)
> {
> - unsigned int latency_req;
> + unsigned int latency_req, next_timer_event;
>
> while (1) {
> /*
> @@ -221,6 +222,9 @@ static void cpu_idle_loop(void)
>
> latency_req = pm_qos_request(PM_QOS_CPU_DMA_LATENCY);
>
> + next_timer_event =
> + ktime_to_us(tick_nohz_get_sleep_length());
> +
> /*
> * In poll mode we reenable interrupts and spin.
> *
> @@ -238,7 +242,8 @@ static void cpu_idle_loop(void)
> tick_check_broadcast_expired())
> cpu_idle_poll();
> else
> - cpuidle_idle_call(latency_req);
> + cpuidle_idle_call(latency_req,
> + next_timer_event);
>
> arch_cpu_idle_exit();
> }

Why do we want to query the next timer in the poll case? Afaict the
other patches don't make use of this either.