[libvirt] Globally Reserve Resources for Host

Dusty Mabe dustymabe at gmail.com
Wed Nov 28 19:27:53 UTC 2012

On Wed, Nov 14, 2012 at 11:22 AM, Dusty Mabe <dustymabe at gmail.com> wrote:
> On Thu, Nov 1, 2012 at 11:32 PM, Dusty Mabe <dustymabe at gmail.com> wrote:
> I think i have a very minimal implementation of what I proposed in my
> original email ("reserving resources for host"). It is not quite as
> featureful as what you discussed with danpb
> (https://www.redhat.com/archives/libvir-list/2011-March/msg01546.html),
> but it is a small amount of work and should be worth the effort.
> As of right now this is specifically for qemu - Basically the idea is
> that right after the cgroup gets created for the qemu driver we will
> set memory and cpu restrictions for the group like so:
> from qemu_driver.c:
> rc = virCgroupForDriver("qemu", &qemu_driver->cgroup, privileged, 1);
> rc = virCgroupSetMemory(&qemu_driver->cgroup, availableMem);
> rc = virCgroupSetCpus(&qemu_driver->cgroup, availableCpus);
> The user will provide values in qemu.conf for "reservedHostMem" and
> "reservedHostCpus" and then availableMem and availableCpus would be
> calculated from that. If no values were provided in the conf then
> simply act as normal and don't enforce any "restrictions".
> We may also want to expose this "setting" in virsh so that we could
> change the value once up and running.
> Does this seem trivial to implement as I suggest? Are there any flaws
> with this idea?

Hey Hey,

Just thought i would ping on this thread to see if anyone had any
input. I may try to code up a minimal implementation and send a patch
if anyone thinks that would be useful in evaluating this feature.

Thanks again!

Dusty Mabe

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