Re: [PATCH 1/3] cpuidle: Store the idle start time stamp

From: Peter Zijlstra
Date: Wed Apr 15 2015 - 08:43:09 EST

On Wed, Apr 15, 2015 at 02:29:06PM +0200, Daniel Lezcano wrote:
> On 04/15/2015 12:20 PM, Peter Zijlstra wrote:
> >On Wed, Apr 15, 2015 at 12:00:22PM +0200, Daniel Lezcano wrote:
> >>+ target_state->idle_stamp = ktime_to_us(ktime_get());
> >
> >ktime_get_ns();
> >
> Hmm, sounds like I missed we are dealing with different units (us / ns) in
> cpuidle / sched.
> Would it make sense to store the time into a ktime structure instead and use
> the relevant function depending on the place we are inspecting the value
> from ?

Why would you ever want to use us? Does ARM enjoy calculating /1000?

Ah, I see the !scalar ktime got whacked, good! At which point the u64 ns
and ktime are the same. That said I prefer the u64 over ktime because
its easier to manipulate.

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