On Tue, 4 Mar 2008 11:01:28 -0800
"Pallipadi, Venkatesh" <venkatesh.pallipadi@xxxxxxxxx> wrote:
> >
> >(On that subject, does anyone except Adam understand that
> >algorithm? Some comments wouldn't hurt...)
>
> Prediction is based on cumulative time till "non expected wakeup". So,
> prediction will come into play only when there are very short wakeups
> due to "unexpected wakeups".
>
Ah, so the measured_us and elapsed_us are trying to keep track of time between non-timer wakeups?
> >So for now, I'm back to thinking that measuring the interval
> >between deep sleeps is the better approach. I could use some
> >ideas for a good clock source though. I haven't dug much
> >deeper than jiffies when it comes to kernel timekeeping.
>
> I think best solution is to use get_last_residency that is already
> there. If the last residency or expected_us is very low, you can avoid
> deep idle states. That way you don't have to depend on jiffies being
> updated at the time you are checking it.
>
I tried using predicted_us and last_measured_us, and those didn't work (see the #if 0 code in my last patch). And since cpuidle_get_last_residency() is part of predicted_us, I don't think it is reporting useful values.
Rgds
--
-- Pierre Ossman
Linux kernel, MMC maintainer http://www.kernel.org
PulseAudio, core developer http://pulseaudio.org
rdesktop, core developer http://www.rdesktop.org
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