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

Ingo Molnar
2007-11-29T10:35:50Z

* 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
> (only) CPU:
> processor : 0
> vendor_id : GenuineIntel
> cpu family : 6
> model : 13
> model name : Intel(R) Pentium(R) M processor 1.50GHz
> stepping : 6
> cpu MHz : 1500.000
> cache size : 2048 KB
> fdiv_bug : no
> hlt_bug : no
> f00f_bug : no
> coma_bug : no
> fpu : yes
> fpu_exception : yes
> cpuid level : 2
> wp : yes
> flags : fpu vme de pse tsc msr mce cx8 sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 ss tm pbe bts est tm2
> bogomips : 2993.49
> clflush size : 64
>
> Any hint?

ah, the cpufreq/acpi/acpi-cpufreq angle is indeed a big clue. I've
Cc:-ed various interested parties.

Ingo