Re: [Xen-devel] A clocksource question

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 03/12/2010 01:13 PM, Joanna Rutkowska wrote:
> > The "clocksource tsc unstable" messages trouble me too BTW. They seem to
> > appear before the hrtimer "interrupt too slow" messages.
> >
> >      
> But this "tsc unstable" message does not seem to be so critical,
They're nothing to worry about.

>   e.g. I
> just started my system (xen clocksource) and started a VM, and got the
> usual hrtimer "slow interrupt" warning, and then all the symptoms
> started, but there no "tsc unstables" warning in dmesg.
>
> However, I previously missed another message, that seem to occur at the
> very beginning of the system life (before I started any other VMs):
>
> Marking TSC unstable due to TSC halts in idle
>    
That doesn't matter because it doesn't use the tsc clocksource.  The Xen 
clocksource uses the tsc hardware register, but it isn't subject to the 
same constraints that the tsc clocksource is.  The tsc clocksource 
calibration is probably getting confused by being on a vcpu.
    J

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