Re: A testing for KVM

[Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org>]

Dong, Eddie wrote:
>> We found that using an hrtimer enabled host with
>> CONFIG_HZ=1000 improves
>> things.  However I don't think that it's as accurate as 7
>> seconds in 20
>> minutes (that's better than 1% accuracy), so probably more work is
>> needed in qemu to correct time drift.
>>
>>     
> Time virtualization for HVM is always a headache, no simple way can
> provide
> accurate source :-(
> Per current KVM time virtualization policy, drop of jiffies or redundant
> jiffies
> may happen frequently. 

There is some code in kvm's qemu to track dropped ticks and reinject 
them.  The code is disabled because it doesn't work well.



> BTW, even in Xen, we are not satisfied with the
> time
> virtualization especially for TSC timer.  
>   

I don't think tsc can be virtualized well.  It's too fast.

> Some modification in guest Linux side is really needed, maybe somebody
> can bring this issue to virtualization mini summit?
>   

Linux already has support for paravirtualized time, we just need to use it.

-- 
error compiling committee.c: too many arguments to function


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