Re: [kvm-devel] [PATCH 0/2][KVM] guest time accounting

[Avi Kivity]

Christian Borntraeger wrote:
> Am Montag, 13. August 2007 schrieb Laurent Vivier:
>   
> > > [copying Ingo and Rusty]
> > >       
>
> @Avi, seems that sourceforge is mangling the cc list?
>
>   

It's not configured to do so.  Can you be more specific?


> > > The patches look good.  A couple of comments:
> > >
> > > - perhaps the new fields should be guarded by a #ifdef CONFIG_HYPERVISOR
> > > (selected by CONFIG_KVM)?  that way the (minor) additional overhead is
> > > only incurred if it can possibly be used.  I imagine that our canine
> > > cousin will want to use this as well.
> > >       
> > There is also a CONFIG_VIRTUALIZATION and a CONFIG_VIRT_CPU_ACCOUNTING (from
> > s390 and powerpc) Which one to use ?
> >     
>
> CONFIG_VIRT_CPU_ACCOUNTING is used for the precise accouting of user,system, 
> steal and irq time on these platforms and is not what you want for the on/off 
> decision. 
>   

Ah, ok.

> > I'm wondering if we can have a more accurate accounting:
> >
> > - For the moment we add all system time since the previous entering to the
> > VCPU to the guest time (and I guess there is some real system time in
> > it ???) 
> > - Perhaps we can sum nanoseconds spent in the VCPU and add it to cpustat
> > when these ns are greater than 1 ms ? (I'm trying to make something in this 
> >     
> way)
>
> If you look at the patch I have posted some minutes ago, I use a method 
> similar to irq_enter and irq_exit to separate real system time from guest 
> time. 

Yes.  This is orthogonal to the current accounting patch and should make 
a nice extension.  It's probably useful with dynamic tick where timer 
interrupts can be rare.


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

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