Re: [KVM timekeeping 10/35] Fix deep C-state TSC desynchronization

[Zachary Amsden]

On 09/15/2010 08:27 AM, Jan Kiszka wrote:
> Am 15.09.2010 14:32, Glauber Costa wrote:
>    
> > On Wed, Sep 15, 2010 at 10:09:33AM +0200, Jan Kiszka wrote:
> >      
> > > > In any case, I'll proceed with the forcing of unstable TSC and HPET
> > > > clocksource and see what happens.
> > > >          
> > > I tried that before, but it did not trigger the issue that kvm-clock
> > > guests no longer boot properly. This only happens if the TSC is marked
> > > unstable.
> > >        
> > even artificially marked unstable ?
> >
> >      
> Yes. As soon as I hack tsc_unstable to 1, things go wrong. When I hack
> it back to 0, guest that wants kvm-clock boots again and seem to run fine.
>
> This is issue #2, I guess. Issue #2 remains that the TSC is marked
> unstable. I have the feeling that this is bogus, maybe due to lacking
> suspend/resume awareness? The tsc clocksource does
>
> 	clocksource_tsc.cycle_last = 0;
>
> on resume...
>
> Jan
>
>    

I have now reproduced this exactly.  Shouldn't be long before I have a 
solution.

Zach
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