[one-users] [ExternalEmail] Trying to understand VCPU and CPU parameters in VM template

[Ruben S. Montero]

Hi

CPU is the capacity you request. The goal is to implement a user
driven consolidation process. The scheduler and tracks the CPU
allocated by each VM so the total CPU (requested) does not exceed the
available one.

For example you have a host with 1 CPU. This means that opennebula can
put there: one VM with CPU=1 or, two VMs with CPU=0.5 Depending on the
workload of the VM you can guide the consolidation actually made in
the cluster.

Also depending on the hypervisor we try to forced that capacity
allocation. For example in xen, the driver uses the credit scheduler
so a 1 CPU VM actually tends to use 2 times the cpu cyles of a 0.5 CPU
VM.

VCPU is just the number of cores of the VM.


Cheers

Ruben
On Fri, Sep 17, 2010 at 8:01 AM,  <Carsten.Friedrich at csiro.au> wrote:
> I just noticed that in the deployment file (I’m deploying to kvm) only the
> VCPU value is used. The CPU value from the template does not appear in the
> deployment.0 file. Does this mean the CPU  parameter is not supported in
> kvm?
>
>
>
> Carsten
>
>
>
> From: users-bounces at lists.opennebula.org
> [mailto:users-bounces at lists.opennebula.org] On Behalf Of
> Carsten.Friedrich at csiro.au
> Sent: Friday, 17 September 2010 10:33
> To: users at lists.opennebula.org
> Subject: [ExternalEmail] [one-users] Trying to understand VCPU and CPU
> parameters in VM template
>
>
>
> From the documentation:
>
>
>
> CPU Percentage of CPU divided by 100 required for the Virtual Machine. Half
> a processor is written 0.5.
>
> VCPU Number of virtual cpus. This value is optional, the default hypervisor
> behavior is used, usually one virtual CPU
>
>
>
> I’m not quite clear how these vlaues are interpreted: E.g. if I specify CPU
> 0.5 and VCPU 2, does this mean I get 2 virtual CPUs each getting 50% of a
> real host CPU, or does this mean I get 2 VCPUs which together can use up to
> 50% of a host CPU, i.e. each VCPU basically gets 25% of a real CPU?
>
>
>
> Cheers,
>
> Carsten
>
>
>
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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