Re: [PATCH 08/14] timer: Export next wake up of a CPU

[Thomas Gleixner <tglx@linutronix.de>]

On Wed, 22 Jun 2016, Lina Iyer wrote:
> +static inline ktime_t tick_nohz_get_next_wakeup(int cpu)
> +{
> +	ktime_t len = { .tv64 = NSEC_PER_SEC/HZ };
> +
> +	/* Next wake up is the tick period, assume it starts now */
> +	return ktime_add(len, ktime_get());

  return tick_next_period;

Will tell you the point where the next tick interrupt is due.

> +}
> +
>  static inline u64 get_cpu_idle_time_us(int cpu, u64 *unused) { return -1; }
>  static inline u64 get_cpu_iowait_time_us(int cpu, u64 *unused) { return -1; }
>  #endif /* !CONFIG_NO_HZ_COMMON */
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index 536ada8..addf3235 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -979,6 +979,19 @@ ktime_t tick_nohz_get_sleep_length(void)
>  	return ts->sleep_length;
>  }
>  
> +/**
> + * tick_nohz_get_next_wakeup - return the next wake up of the CPU
> + *
> + * Called with interrupts disabled on the cpu

So why are you handing in the (undocumented) cpu argument if its called on
that cpu anyway?

> + */
> +ktime_t tick_nohz_get_next_wakeup(int cpu)
> +{
> +	struct clock_event_device *dev =
> +			per_cpu(tick_cpu_device.evtdev, cpu);
> +
> +	return dev->next_event;

Then this becomes

     return __this_cpu_read(tick_cpu_device.evtdev)->nextevt;

Thanks,

	tglx