libvirt users - Jan 2015 - Re: questions around using numatune/numa/schedinfo

Hi,

I'm running into some problems with libvirt and hoping someone can point me
at
some instructions or maybe even help me out.


First, are there any requirements on qemu version in order to use the
"numatune"
and/or "cpu/numa/cell" elements?  Or do they use cgroups and not the
native qemu
numa support?


Second, are there any instructions on how to set up cgroups?  I initially
hadn't
had cgroups mounted and running "virsh schedinfo <domain>" gave
an error.  So I
mounted "/sys/fs/cgroup/memory" and "/sys/fs/cgroup/cpu" and
restarted libvirtd
but running "virsh schedinfo <domain>" still gives an error:

root@compute-1:~# virsh schedinfo 8
Scheduler      : Unknown
error: Requested operation is not valid: cgroup CPU controller is not mounted

What am I missing?


Thanks,
Chris

On 23.01.2015 19:46, Chris Friesen wrote:
> Hi,
> 
> I'm running into some problems with libvirt and hoping someone can
point
> me at some instructions or maybe even help me out.
> 
> 
> First, are there any requirements on qemu version in order to use the
> "numatune" and/or "cpu/numa/cell" elements?  Or do they
use cgroups and
> not the native qemu numa support?
For numatune you need a qemu with 'memory-backend-{ram,file}' objects.
Those were introduced in qemu-2.1.0. As of libvirt, you'll need
libvirt-1.2.7 at least. Although the newer the better - there were
couple of fixes recently.
> 
> 
> Second, are there any instructions on how to set up cgroups?  I
> initially hadn't had cgroups mounted and running "virsh schedinfo
> <domain>" gave an error.  So I mounted
"/sys/fs/cgroup/memory" and
> "/sys/fs/cgroup/cpu" and restarted libvirtd but running
"virsh schedinfo
> <domain>" still gives an error:
> 
> root@compute-1:~# virsh schedinfo 8
> Scheduler      : Unknown
> error: Requested operation is not valid: cgroup CPU controller is not
> mounted
> 
> What am I missing?
> 
> 
What's the libvirt version?

Michal

On Mon, Jan 26, 2015 at 01:08:50PM +0100, Michal Privoznik
wrote:
> On 23.01.2015 19:46, Chris Friesen wrote:
> > Hi,
> > 
> > I'm running into some problems with libvirt and hoping someone can
point
> > me at some instructions or maybe even help me out.
> > 
> > 
> > First, are there any requirements on qemu version in order to use the
> > "numatune" and/or "cpu/numa/cell" elements?  Or do
they use cgroups and
> > not the native qemu numa support?
> 
> For numatune you need a qemu with 'memory-backend-{ram,file}'
objects.
> Those were introduced in qemu-2.1.0. As of libvirt, you'll need
> libvirt-1.2.7 at least. Although the newer the better - there were
> couple of fixes recently.
Recently I did a test here with KVM nested virtualization (I was testing
from git, so the commits are noted too):

   
https://kashyapc.fedorapeople.org/virt/openstack/nova-libvirt-numa-testing/Notes-test-libvirt-NUMA-with-DevStack.txt

The libvirt guest XML configs are in that directory too.

The above test is based on upstream notes in context of OpenStack Nova,
written by Daniel Berrangé:

   
https://review.openstack.org/#/c/131818/6/doc/source/devref/testing/libvirt-numa.rst


-- 
/kashyap

On 01/26/2015 06:08 AM, Michal Privoznik wrote:
> On 23.01.2015 19:46, Chris Friesen wrote:
>> First, are there any requirements on qemu version in order to use the
>> "numatune" and/or "cpu/numa/cell" elements?  Or do
they use cgroups and
>> not the native qemu numa support?
>
> For numatune you need a qemu with 'memory-backend-{ram,file}'
objects.
> Those were introduced in qemu-2.1.0. As of libvirt, you'll need
> libvirt-1.2.7 at least. Although the newer the better - there were
> couple of fixes recently.
Okay, thanks.  I saw the recent fixes in the git logs.
>> Second, are there any instructions on how to set up cgroups?  I
>> initially hadn't had cgroups mounted and running "virsh
schedinfo
>> <domain>" gave an error.  So I mounted
"/sys/fs/cgroup/memory" and
>> "/sys/fs/cgroup/cpu" and restarted libvirtd but running
"virsh schedinfo
>> <domain>" still gives an error:
>>
>> root@compute-1:~# virsh schedinfo 8
>> Scheduler      : Unknown
>> error: Requested operation is not valid: cgroup CPU controller is not
>> mounted
>>
>> What am I missing?
>>
>>
>
> What's the libvirt version?

Libvirt is 1.2.8.

Chris