Re: PROBLEM: system clock slow on Athlon AMD64 since 2.6.21

From: Gerard H. Pille
Date: Mon Jun 11 2007 - 06:51:43 EST

From: Robert Hancock <hancockr@xxxxxxx>
To: Mikael Pettersson <mikpe@xxxxxxxx>
CC: ghpille@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx
Subject: Re: PROBLEM: system clock slow on Athlon AMD64 since 2.6.21
Date: Sun, 10 Jun 2007 12:02:00 -0600

Mikael Pettersson wrote:
On Fri, 08 Jun 2007 10:14:03 +0200, Gerard H. Pille wrote:
[1.] One line summary of the problem:
Since I switched from 2.6.20 to 2.6.21 on my Athlon AMD64 laptop, the system time is slow - about 1' on 15'.

According to your system description it seems that you have a
Targa Visionary laptop with a VIA chipset and a Mobile Athlon64.
If so, then you probably have the same problem I reported some time
ago: see <>
and the followup messages. The conclusion was that the chipset's
ACPI PM timer slows down when the CPU is in C2.

The workaround is to boot with processor.max_cstate=1.

Which, if true, is extremely bizarre, as the whole point and reason for existence of the ACPI PM timer is that it NOT do this, and remain at the same rate regardless of CPU power management changes..

Robert Hancock Saskatoon, SK, Canada
To email, remove "nospam" from hancockr@xxxxxxxxxxxxx
Home Page:

So I shouldn't have started a new bug report, sorry. I had once read your problem report, but I could not relocate it afterwards.

If I can provide any assistance in debugging, please let me know.



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