Re: [kvm-devel] Réf. : Re: [PATCH 0/4] Virtual Machine Time Accounting

On 8/21/07, Christian Borntraeger [off-list ref] wrote:

Am Montag, 20. August 2007 schrieb Glauber de Oliveira Costa:

quoted

Although I don't know KVM to a that deep level, I think it should be
possible to keep the virtual cpus in different process (or threads),
and take the accounting time from there. Perfectly possible to know
the time we spent running (user time), and the time the hypervisor
spent doing things on our behalf (system time).

I disagree here. First thing, you dont want to have the virtual cpu in a
different process than the hypervisor control code for that cpu. Otherwise
communication has to be made via IPC.
Secondly, Its not qemu/kvm that does the accouting. Its existing userspace
code like top/snmp agents and clients! etc. that would require additional
knowledge which thread is guest code.

Yes, the second argument kills me, and I think it leaves no further
room from discussion in my side. Thanks for the enlightenment.

I personally like the approach Laurent has taken. Maybe it needs some polish
and maybe we want an account_guest_time function, but in general I think he
is doing the right thing.

Now, me too.

-- 
Glauber de Oliveira Costa.
"Free as in Freedom"
http://glommer.net

"The less confident you are, the more serious you have to act."