[libvirt-users] libvirt/qemu and cgroups

[Daniel P. Berrange]

On Mon, Feb 10, 2014 at 12:29:10AM +0100, arnaud gaboury wrote:
> Dear list,
> 
> I am building a Arch server on my Arch box.
> My tools are QEMU/KVM and libvirt to manage the guest, systemd as
> system manager.
> 
> I am looking at implementing the Linux Control Groups facilities for
> resource management. Even after long hours of reading, I am not quite
> sure about how to deal with the cgroups facilities.
> 
> First, do I really need to care about all that, or libvirt and systemd
> will manage the resource in an efficient way right out of the box?

The precise answer depends on which version of systemd you have. In
any systemd host though, systemd should ensure all the filesystems
are mounted correctly. If you have libvirt >= 1.1.1 and systemd >= 205
then you can use its "slice" and "scope" concepts to setup grouping
of VMs. If you have older systemd,  then you have to setup groups
manually. There's some guidance on setting up groups here

   http://libvirt.org/cgroups.html

If you have systemd >= 205 then you can ignore cgconfig.conf entirely.
For earlier version, you can use cgconfig.conf to setup the groups
only.

Daniel
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