Re: [BUG] jiffies counter leaps in 2.6.24-rc3

Dave Jones
2007-11-29T17:47:21Z

On Thu, Nov 29, 2007 at 11:35:11AM +0100, Ingo Molnar wrote:

> * Stefano Brivio <stefano.brivio@polimi.it> wrote:
>
> > Ok, I found out how to reliably reproduce this bug. The root session issue
> > was a bit weird, but I noticed I usually switch to root only when I need to
> > change the CPU frequency. And here's what happens:
> >
> > # cpuspeedy min
> > [after some time...]
> > Nov 29 09:42:31 morte [ 4408.722597] b43-phy0 ERROR: PHY transmission error
> >
> > # cpuspeedy max
> > Nov 29 09:42:41 morte [ 1177.238599] wmaster0: STA 00:14:c1:35:8d:eb Average rate: 540 (2160/4)
> >
> > It looks like jiffies get scaled exactly by a 3.75 factor, which is
> > <max_frequency>/<min_frequency> here. I use acpi-cpufreq and this is my
>
> ah, the cpufreq/acpi/acpi-cpufreq angle is indeed a big clue. I've
> Cc:-ed various interested parties.

Hmm, what's in /sys/devices/system/clocksource/clocksource0/current_clocksource ?

adjust_jiffies() always gets called on a speed transition. I'm wondering
if perhaps we shouldn't do that if we're using something other than
the tsc for timekeeping.

Dave

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