linux-kernel - RE: [linux-pm] [RFC-PATCH] Improve Menu Governor Prediction of interrupted C states.

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Date:	Tue, 5 Aug 2008 20:24:44 -0500
From:	"Woodruff, Richard" <r-woodruff2@...com>
To:	"Wei, Gang" <gang.wei@...el.com>,
	Linux Power Management List <linux-pm@...ts.osdl.org>
CC:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: RE: [linux-pm] [RFC-PATCH] Improve Menu Governor Prediction of
 interrupted C states.

Hi,

> I also found current cpuidle Menu governor should have some problems
> while predicting next non-expected break-event after some expected
> break-events. The measured_us/elapsed_us/predicted_us will become
> larger
> and larger once (measured_us + BREAK_FUZZ >= data->expected_us -
> target->exit_latency). The major point is that it should be
> last_residency, not measured_us, that need to be used to do comparing
> and distinguish between expected & non-expected events.
>
> Below is my draft patch (not tested) for this. It is simple and should
> also be effective for high interrupt rates case.

This does seem to give better guesses.  However, first tests are not showing as well as the irq time stamp version I posted.

I'll need to grab some hardware trace to see what is going on.

Thanks,
Richard W.

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