Re: cpufreq longhaul locks up

[john stultz <johnstul@us.ibm.com>]

On Fri, 2007-05-04 at 23:02 +0200, Jan Engelhardt wrote:
> On May 4 2007 13:37, john stultz wrote:
> >> 
> >> I found that setting the cpufreq governor to ondemand making the box 
> >> lock up solid in 2.6.20.2 and 2.6.21 after a few seconds. Sysrq 
> >> does not work anymore, and the last messages are:
> >> 
> >> May  3 19:16:58 cn kernel: longhaul: VIA C3 'Nehemiah C' [C5P] CPU 
> >> detected.  Powersaver supported.
> >> May  3 19:16:58 cn kernel: longhaul: Using northbridge support.
> >> May  3 19:17:22 cn kernel: Time: acpi_pm clocksource has been installed.
> >> May  3 19:17:22 cn kernel: Clocksource tsc unstable (delta = -136422685 
> >> ns)
> >
> >What happens if you boot wihtout the ondemand governor but w/
> >clocksource=acpi_pm ?
> 
> I always let it boot with the default gov (performance), then
> use cpufreq-set to change it.
> 
> acpi_pm+performance behaves like tsc+performance, which works
> 
> When switching from tsc+performance to (tsc+)ondemand, acpi_pm gets
> used because of the unstable tsc (of course, since we changed
> frequency and the cpu does NOT have constant_tsc), so it's
> becoming acpi_pm+ondemand naturally.

Ok. I just wanted to make sure it wasn't the ACPI PM that was broken and
when the system switched to it it was causing the hang.

> Switching from acpi_pm+performance to acpi_pm+ondemand also
> locks up after a few minutes.

Yep. Sounds like an ondemand issue. Thanks for verifying this for me.

-john

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