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

Christian Borntraeger
2007-08-13T14:22:27Z

Am Montag, 13. August 2007 schrieb Avi Kivity:

> Laurent's patch gives the best of both worlds: on old 'top', you get
> guest time accounted as user time, while on new 'top' it is accounted
> separately. This is done by reporting user time as the sum of the real
> user time and guest time. A newer 'top' can subtract guest time from
> user time to get the correct statistic.

Yes that looks promising. If I recall correctly we had some strange top
behaviours when we introduced the steal time. Old top added the steal time to
idle. We should check that.

>
>
> > 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.
> >
>
> Okay, so the code should be under that config option, and kvm should
> select it.

No hurry..that was specific to our implementation, not KVM :-)
Besided that, Ingo changed the accouting with his CFS scheduler, and I still
have to figure out how CONFIG_VIRT_CPU_ACCOUNTING can be properly integrated
in CFS.

Christian