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

Pasi Kärkkäinen pasik at iki.fi
Thu Aug 21 09:52:20 UTC 2008

On Wed, Aug 20, 2008 at 07:37:25AM -0500, Michael Ekstrand wrote:
> "Akemi Yagi" <amyagi at gmail.com> writes:
> > On Tue, Aug 19, 2008 at 5:55 PM, Michael Ekstrand <michael at elehack.net> wrote:
> >> I'm running VMware Server 1.0.6 on a CentOS 5.2 host and am having some
> >> clock difficulties.
> >>
> >> Host OS is x86_64 running on 1.9 GHz AMD Sempron, nVidia chipset.
> >>
> >> Guest OS's are 32-bit FreeBSD (clock works fine after disabling ACPI,
> >> setting the clock source to the PIT, and running the guest tools), WinXP
> >> (unknown clock status), and i686 CentOS 5.2 (here is the problem).
> >>
> >> I've tried pretty much everything to try to fix it.  I have host.cpukHz,
> >> host.noTSC, and ptsc.noTSC set in /etc/vmware/config.  I've booted my
> >> kernel with noapic, nosmp, noacpi, divider=10.  Sadly, I hit the
> >> clocksource=pit with divider bug, so I have not been able to boot with
> >> both that and divider=10, although clocksource=pit without a divider
> >> also does not work.  I even built a custom kernel with SMP and APIC
> >> disabled, CPU_HZ=100, and booted with clocksource=pit noacpi, and it
> >> also gains time.
> >>
> >> Could anyone provide a recommendation as to what I can do to fix this problem?
> >
> > 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

IIRC clocksource=pit should not be used on modern kernels.. 

Can you try clocksource=acpi_pm ? with tools.synctime = "true" flag in your
vmx file.

(if it's available in your kernel).

There was some nice summary about different clocksource= options etc and in
what kernels do they work.. just can't remember the url now.

-- Pasi

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