[one-users] Relationship of cpu usages

Carlos Martín Sánchez cmartin at opennebula.org
Fri Apr 26 01:56:35 PDT 2013

Hi there,

On Fri, Apr 26, 2013 at 9:09 AM, Christoph Pleger <
Christoph.Pleger at cs.tu-dortmund.de> wrote:

> Hello,
> > I have a new question about that.
> >
> > On http://opennebula.org/documentation:rel3.8:kvmg, I read about
> cgroups:
> >
> > "So, thanks to cgroups a VM with CPU=0.5 will get half of the physical
> > cycles than a VM with CPU=1.0."
> >
> > How can a second VM get half of the physical CPU cycles of a first VM if
> > the first VM is defined to use 100 % of the CPU cycles?
I'm not that much familiar with cgroups, but the way I understand it the
first VM does not get 100%, it will get 1024 shares out of 1536 (2/3 of cpu

> Does really nobody know that? Or was my question too difficult to
> understand or just too stupid?

Relax buddy, this is a best-effort mailing list, not a commercial support

> By the way, if every cloudnode has 64 cpu cores and a VM is defined to use
> 64 virtual cpus, does for example CPU=0.8 mean 80 percent of one cpu core
> or 80 percent of 64 cpu cores?

It will get allocated 80 from the total of 6400 Host CPU. The number of
virtual CPUs is not related to the real CPU allocated.


> Regards
>   Christoph
Carlos Martín, MSc
Project Engineer
OpenNebula - The Open-source Solution for Data Center Virtualization
www.OpenNebula.org <http://www.opennebula.org/> | cmartin at opennebula.org |
@OpenNebula <http://twitter.com/opennebula> <cmartin at opennebula.org>
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