Re: [RFC PATCH v2 5/8] timers: keep sleep length updated as needed

Rafael J. Wysocki
2017-10-14T01:06:01Z

On Saturday, September 30, 2017 9:20:31 AM CEST Aubrey Li wrote:
> sleep length indicates how long we'll be idle. Currently, it's updated
> only when tick nohz enters. These patch series make a new requirement
> with tick, so we should keep sleep length updated as needed

So what exactly would be the problem with leaving things as they are?

> ---
> kernel/time/tick-sched.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c
> index d663fab..94fb9b8 100644
> --- a/kernel/time/tick-sched.c
> +++ b/kernel/time/tick-sched.c
> @@ -1008,8 +1008,11 @@ void tick_nohz_irq_exit(void)
> */
> ktime_t tick_nohz_get_sleep_length(void)
> {
> + struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev);
> struct tick_sched *ts = this_cpu_ptr(&tick_cpu_sched);
>
> + ts->sleep_length = ktime_sub(dev->next_event, ktime_get());
> +
> return ts->sleep_length;
> }
>
>

I probably wouldn't do it this way ...