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SubjectRe: [RFC][PATCH 2/2] ACPI: handle timer ticks proactively
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On Tue, 2006-09-05 at 11:03 +0200, Pavel Machek wrote:
> Hi!
>
> > > > This patch takes advantage of the infrastructure introduced in the last
> > > > patch, and allows the processor idle algorithm to proactively choose a
> > > > c-state based on the time the next timer interrupt is expected to occur.
> > > > It preserves the residency metric, so the algorithm should, in theory,
> > > > remain effective against bursts of activity from other interrupt
> > > > sources.
> > > >
> > > > This patch is mostly intended to be illustrative. There may be some
> > > > "#ifdef CONFIG_ACPI" issues, and I would appreciate any advice on
> > > > implementing this more cleanly.
> >
> > Okay, just to get you some feedback:
> >
> > It seems to change things a _lot_. Power consumption with usb modules
> > loaded went from 14315mW to 13800mW -- that is huge
> > deal. Unfortunately something strange is going on: with stock kernel,
> > power consumption is mostly constant. With your patch, it varies a
> > lot, at 2 second timescale.
> >
> > Power consumption with usb unloaded (only way to get reasonable power
> > on x60) went from stable 10450mW to something rapidly changing, and
> > probably even worse than original:
>
> I also noticed that with your patch, bus master activity tends to be constant?!

Is this the case even when userspace touches the disk? On my hardware I
see a constant flow of short BM activity bursts.

Thanks,
Adam


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