Date: Wed, 15 Apr 2015 14:42:46 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Daniel Lezcano <daniel.lezcano@linaro.org>
Cc: rjw@rjwysocki.net, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org,
        nicolas.pitre@linaro.org
Subject: Re: [PATCH 1/3] cpuidle: Store the idle start time stamp
Message-ID: <20150415124246.GW5029@twins.programming.kicks-ass.net>
References: <1429092024-20498-1-git-send-email-daniel.lezcano@linaro.org>
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 <552E5992.2050404@linaro.org>
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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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