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

Laurent Vivier
2007-08-13T14:22:50Z

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Christian Borntraeger wrote:
> Am Freitag, 10. August 2007 schrieb Laurent Vivier:
>> The aim of these two patches is to measure the CPU time used by a virtual
>> machine. All comments are welcome... I'm not sure it's the good way to do
> that.
>
> I did something similar for or s390guest prototype, that Carsten posted in
> May. I decided to account guest time to the user process instead of adding a
> new field to avoid hazzle with old top. As you can read in the patch comment,
> I personally prefer a new field if we can get one.
>
> My implementation uses a similar mechanism like hard and softirq. So I have an
> sie_enter an sie_exit and a task_is_in_sie function - like irq_enter and
> irq_exit. The main difference is based on the fact, that s390 has precise
> accouting for irq, steal, user and system time, and therefore my patch is
> based on architecture specifc code using CONFIG_VIRT_CPU_ACCOUNT.
>
> In general my patch has the same idea as your patch, so I am going to review
> your patch and see if it would fit for s390.
>
> For reference this is the (never posted) old patch for our virtualisation
> prototype. It wont work with kvm but it gives you the idea what we had in
> mind on s390.
>

thank you for your comment.

As virtualization becomes very popular, perhaps we should implement something
which could be used by all linux supported architectures ?
(yes, I know it's non-sense for archs like m68k...)
But my [PATCH 1/2] can be a good start (adding "guest" in cpustat)
As guest accounting is hw dependent, I think we should add a hook in the
accounting functions.

Laurent
--
------------- Laurent.Vivier-6ktuUTfB/bM@public.gmane.org --------------
"Software is hard" - Donald Knuth

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