[CentOS-virt] VMware Server clock woes (running too fast)

Akemi Yagi amyagi at gmail.com
Wed Aug 20 14:52:11 UTC 2008

On Wed, Aug 20, 2008 at 5:37 AM, Michael Ekstrand <michael at elehack.net> wrote:
> "Akemi Yagi" <amyagi at gmail.com> writes:

>> I understand you built a 100Hz kernel, but *just in case*, you might
>> want to try CentOS-supplied 100Hz kernel (kernel-vm) available from:
>> http://people.centos.org/tru/kernel-vm/
> Just tried it, and it doesn't seem to work. I used the following
> parameters:
>  nosmp noapic nolapic noacpi clocksource=pit
>> Also, enable time sync with host if that has not been done.
> Already done, and was active throughout the problems described above.
> I seem to remember seeing somewhere or another something about a
> different set of timing devices available on 64-bit vs. 32-bit.

cat /sys/devices/system/clocksource/clocksource0/available_clocksource

will show you available options.  It is different between 32-bit and 64-bit.

> was previously using 32-bit Debian Etch as the host OS on this same
> hardware with an upgraded (2.6.22) kernel, I had no noticable timing
> problems on the FreeBSD guest (didn't run Linux guests enough to notice
> anything).  After switching to 64-bit CentOS host OS, the FreeBSD guest
> clock started running fast, but it responded to adjustments and keeps in
> line with the setup described above.  Is it possible that running the
> 64-bit host environment is what is causing my problems?  Are there host
> options I can tweak to try to improve the situation?

On the *host* side, you can try disabling power management and other
things. For example:

apm=off acpi=off noapic


> - Michael

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