extreme clock drift

Support for the other architectures (X86_64, IA-64, and PowerPC)
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rbdavis
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Joined: 2007/07/31 23:49:00

extreme clock drift

Post by rbdavis » 2008/07/01 02:11:59

Hello,

I am experiencing some pretty heinous clock drift on my x86_64 laptop since installing CentOS 5.1, gaining an additional 75 seconds for every minute of real time. The machine is a Hypersonic-PC Aviator AX6 laptop (AMD Athlon 64).

I have found various references to this problem in other forums but they are mostly either very old (I can't believe this hasn't been fixed yet!) or involve special circumstances which do not apply to me, e.g., using VMware. These posts recommend any or all of the following boot options as workarounds:

clock=pmtmr
clock= pit
acpi=off
noapic
notsc
acpi=noirq irqfixup nolapic pci=biosirq

Only the following worked for me:

acpi=off
notsc

Some people, however, have reported equally unacceptable side-effects for these workarounds, such as highly degraded network performance.

Can anyone tell me what is going on here, is this a known bug, is there a preferred workaround from the set shown above (or otherwise) and what are the other ramifications of these workarounds? Exactly what do 'acpi=off'' and/or 'notsc' do, anyway? Are there any reasons I would *not* want to do either or both of these things?

Thanks,

Roger Davis
rbd@hawaii.edu

rbdavis
Posts: 14
Joined: 2007/07/31 23:49:00

Re: extreme clock drift

Post by rbdavis » 2008/07/01 02:16:23

PS: Sorry, should have added I am running 2.6.18-53.1.19.el5.

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AlanBartlett
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Re: extreme clock drift

Post by AlanBartlett » 2008/07/01 10:22:37

You'll find all the boot command-line parameters listed here - http://www.centos.org/docs/5/html/5.1/Installation_Guide/ch-bootopts-x86.html

You also might like to upgrade the kernel you are running. The last kernel for [b]CentOS 5 update 1[/b] was 2.6.18-53.1.21.el5 whilst the current kernel for [b]CentOS 5 update 2[/b] is 2.6.18-92.1.6.el5.

rbdavis
Posts: 14
Joined: 2007/07/31 23:49:00

Re: extreme clock drift

Post by rbdavis » 2008/07/01 18:17:47

Thanks for the reference on the boot options, Alan. Unfortunately the two options that actually help work around my problem (acpi=off and notsc) are not even mentioned there. Any idea where I could learn more about what these things actually do?

Thank you!

Roger

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AlanBartlett
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Re: extreme clock drift

Post by AlanBartlett » 2008/07/02 12:21:57

Sorry [b]Roger[/b], I didn't check. :oops:

[b]acpi[/b] - Advanced Configuration and Power Interface. You can read the specification (as written by its developers) here - http://www.acpi.info/spec.htm

[b]notsc[/b] - no tsc. A [i]Google[/i] search turns up this - http://www.google.co.uk/search?q=notsc&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a
and this - http://www.google.co.uk/search?q=tsc+linux+kernel&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-GB:official&client=firefox-a

Hope this is some help.

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