Re: PM-Timer clock source is slow. Try something else: How slow?What other source(s)?

From: Srinivasa Ds
Date: Thu Nov 30 2006 - 00:17:32 EST


john stultz wrote:
On Wed, 2006-11-29 at 16:56 -0800, Linda Walsh wrote:
I recently noticed this message in my bootup that I don't remember
from before:

PCI: Probing PCI hardware (bus 00)
* Found PM-Timer Bug on the chipset. Due to workarounds for a bug,
* this clock source is slow. Consider trying other clock sources

This basically means that your chipset has a bug which requires the ACPI
PM timer to be read three times in order to get a valid reading.

This will cause gettimeofday/clock_gettime to take longer to execute,
which is what is meant by "slow" (rather then the counter's frequency
being incorrect).

How would this affect my clock? It says to try another
clock source, what type of clock source would it be suggesting I
use? Another chip already in the computer?
Yes.
It is an Intel 440BX
chipset; on an Dell motherboard. Would that be likely to have
another chip source that is compensating?
You can change the clock source using "clock=" kernel parameter. Please refer to Documentation/kernel-parameters.txt file of kernel source.
I don't notice a significant clock slowdown, but I'm running NTP,
so that could be masking the problem.

Unless you're running performance critical programs that utilize
gettimeofday/clock_gettime, you probably won't notice anything. Time
should still function properly. If you are having performance issues,
you can try using a different clocksource (the TSC is probably safe, but
not necessarily).

thanks
-john



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Thanks
Srinivasa DS
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