Re: [PATCH] cpuidle: Change ktime_get() with local_clock()

From: Peter Zijlstra
Date: Wed Apr 20 2016 - 08:13:25 EST


On Thu, Apr 14, 2016 at 09:23:54PM +0200, Daniel Lezcano wrote:
> @@ -217,7 +217,11 @@ int cpuidle_enter_state(struct cpuidle_device *dev, struct cpuidle_driver *drv,
> if (!cpuidle_state_is_coupled(drv, entered_state))
> local_irq_enable();
>
> - diff = ktime_to_us(ktime_sub(time_end, time_start));
> + /*
> + * local_clock() returns the time in nanosecond, let's shift
> + * by 10 (divide by 1024) to have microsecond based time.
> + */
> + diff = (time_end - time_start) >> 10;

Changelog fails to explain the ramifications of this change...