[one-users] The CPU template variable doesn't seem to work ...

[Ruben S. Montero]

Hi

CPU capacity is a hint for the scheduler. If a physical host has 2 CPU
(200), means that OpenNebula would not allocate VMs whose aggregated
capacity is greater than 200. Now, the actual sharing of the physical
CPU's is managed by the hypervisor.

Currently we are using the credit scheduler in Xen so the CPU usage of
VMs tends to that in CPU value, see [1] for more info. KVM is using
the kernel process scheduler, and currently we do not set priorities
or any other scheduling attribute. So I'd say that is the expected
behavior.

Cheers

Ruben


[1] http://wiki.xensource.com/xenwiki/CreditScheduler


On Wed, Apr 28, 2010 at 2:59 PM, florian chazal <florianchazal at gmail.com> wrote:
> Hi all,
>
> I don't if I guess well but I did some test of CPU varaible and I obtain
> this result :
>
> - CPU = 25%, VCPU = 1 (default value) :  VM has 1 CPU and can use 100\% of
> it,
> - CPU = 100%, VCPU = 1 : VM has 1 CPU and can use 100% of it,
> - CPU = 200%, VCPU = 1 : VM has 1 CPU  and can use 100% of it,
> - CPU = 100%, VCPU = 2 : VM has 2 CPUs and can use 100% of them, that is to
> say 200\%,
> - CPU = 200%, VCPU = 2 : VM has 2 CPUs and can use 100% of them, that is to
> say 200\%.
>
> Therefore I conclued that the manager is ont using the variable or is not
> able to limit the CPU comsuption of one vm on a single processor.
> Am I right? Is it a bug?
> Thanks in advance .
>
>
> ps :  I did this test with a c script with an infinite loop launch on the vm
> and I check the result on the node with a htop command.
> --
> Florian Chazal
>
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>



-- 
Dr. Ruben Santiago Montero
Associate Professor (Profesor Titular), Complutense University of Madrid

URL: http://dsa-research.org/doku.php?id=people:ruben
Weblog: http://blog.dsa-research.org/?author=7