Re: Clock off in guest

[Koen Vermeer <koen@vermeer.tv>]

On Wed, 2008-02-13 at 09:58 -0800, Uri Lublin wrote:
> The host kernel or kvm.
> If you choose to upgrade your host kernel (and kvm that comes with
> it), make sure
> you are using recent kvm-userspace too (e.g. kvm-60).

Running 2.6.23 on the host with kvm 60 (userspace) and kvm-source 60
(modules).
> 

> >> Or as an alternative, probably not as good, sometimes (when the
> guest's
> >> clocksource is PIT) adding '-tdf' to the command line helps.
> >I cannot find this in man kvm or man qemu.
> I'm not sure about the man pages, but kvm/qemu's help says:
> bash$ /usr/bin/kvm -h | grep tdf
> -tdf            inject timer interrupts that got lost
> 
It doesn't seem to be mentioned in the man pages, but it is indeed there
when running 'kvm --help'.


> Yes, try adding it to the command line that starts the guest
> (executable name may vary):
>    /usr/bin/kvm [kvm-params] -tdf
> Also tdf (time drift fix) only works when using PIT+PIC (no APIC) so
> sometimes it's helpful
> to also add -no-acpi:
>    /usr/bin/kvm [kvm-params] -tdf -no-acpi
> 
I tried both -tdf and -tdf -no-acpi, but it didn't change anything. I
did notice some lines on the host saying 

time drift is too long, 60 seconds were lost

which weren't there when running without '-tdf'.


You were saying -tdf only works when using PIT+PIC, but, as far as I can
tell, the guest is still using tsc. Should I add a kernel parameter like
clocksource=pit to the guest?

I appreciate the help!

Koen


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