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

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Message-ID: <20071129095034.24b3fc59@morte>
Date:	Thu, 29 Nov 2007 09:50:34 +0100
From:	Stefano Brivio <stefano.brivio@...imi.it>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	linux-kernel@...r.kernel.org, Ingo Molnar <mingo@...e.hu>,
	Michael Buesch <mb@...sch.de>
Subject: Re: [BUG] jiffies counter leaps in 2.6.24-rc3

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?

--
Ciao
Stefano
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