On Wed, 2 May 2007, Martin Dieringer wrote:
> On Tue, 1 May 2007, Martin Dieringer wrote:
>
> > On Tue, 1 May 2007, Clayton Milos wrote:
> >
> >>> Hi,
> >>>
> >>> I get about half a second time offsets after 10 seconds, and more
> >>> than 100s after half an hour or so.
> >>> I think it has to do with powerd, if I kill that, the time stays correct.
> >>> It happens both on a Compaq nc4000 and an IBM ThinkPad T42p laptop.
> >>>
> >>> Can this be solved?
> >>> thanks
> >>> m.
> >>
> >> This has got to do with the speed stepping of the CPU to save battery.
> >> Far as I know there's no fix yet.
> >>
> >> Guys is it possible to hack powerd to change a sysctl variable when it
> >> changes the CPU frequency or isn't it that simple?
> >
> >
> > Another effect of the problem seems to be the intermittent sound
> > output. Playback is ok when powerd is killed.
> > When changing freq by sysctl, I still get hickups in sound, so this
> > would be no solution.
>
> the hiccups have reappeared, so they are not related to powerd.
>
> I still have 0.5 seconds time offsets after 10 minutes, on the
> thinkpad, without powerd...
I'm wondering if this might have to do with power_profile's settings of
hw.acpi.cpu.cx_lowest when moving from AC to battery power?
If you don't specify {performance,economy}_cpu_freq="NONE" in rc.conf,
powerd and power_profile will argue the toss on every switch of line
state (running powerd -v illustrates this nicely). powerd, however,
does not as yet affect the cx setting also.
The default values of {performance,economy}_cx_lowest are "HIGH" and
"LOW" on my 6.1-R system, but "HIGH" and "HIGH" on my 5.5-STABLE box,
though the latter isn't using ACPI; you might want to check these in
your /etc/defaults/rc.conf and override them in rc.conf if necessary.
Anyway, this is a bit of a stab in the dark, but try setting in rc.conf
economy_cx_lowest="C2" which has the effect of having power_profile set
hw.acpi.cpu.cx_lowest="C2" on line state change rather than the "LOW"
value, probably C3, to see if this might affect your timing problem?
On my T23 on 6.1-R, I noticed that the C3 state is never used (as shown
by hw.acpi.cpu.cx_usage) unless the machine was booted up on battery :-/
I also seem to recall reading that C3 may be problematic on some boxes,
possibly related to timing problems, but like Jeremy I'm not sure where.
Cheers, Ian
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