Re: A testing for KVM

> I'm not sure if this affects the TSC theory or not, but note that the
> host and guest have 250Hz PIT configured in the config.  E.g. both
> kernels are programming the PIT to 250Hz, but guest is only
> seeing 125Hz
> ticks.  If I "fix" the lost interrupt to bring the ticks to a true
> 250Hz, wall-clock time runs at 2x.  Could it still be a TSC
> virtualization problem under these conditions? (I dont know much about
> TSC, so I just thought I would clarify this detail)

Yes, though I am not sure if it is 2X but anyway faster in guest.
We saw this in Xen but not that much. probably +20-30%.

>From your observation, it looks like guest OS add back 100% 
lost ticks which is quit more than I observed in Xen. Probably it
has additional issue besides TSC. (I won't say it is a TSC
virtualization issue, but PIT virtualization issue :-(
Eddie

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