[Openstack] HPC with Openstack?

Daniel P. Berrange berrange at redhat.com
Tue Dec 6 10:02:25 UTC 2011

On Mon, Dec 05, 2011 at 09:07:06PM -0500, Lorin Hochstein wrote:
> On Dec 4, 2011, at 7:46 AM, Soren Hansen wrote:
> > 2011/12/4 Lorin Hochstein <lorin at isi.edu>:
> >> Some of the LXC-related issues we've run into:
> >> 
> >> - The CPU affinity issue on LXC you mention. Running LXC with OpenStack, you
> >> don't get proper "space sharing" out of the box, each instance actually sees
> >> all of the available CPUs. It's possible to restrict this, but that
> >> functionality doesn't seem to be exposed through libvirt, so it would have
> >> to be implemented in nova.

I recently added support for CPU affinity to the libvirt LXC driver. It will
be in libvirt 0.9.8. I also wired up various other cgroups tunables including
NUMA memory binding, block I/O tuning and CPU quota/period caps.

> >> - LXC doesn't currently support volume attachment through libvirt. We were
> >> able to implement a workaround by invoking "lxc-attach" inside of OpenStack
> >> instead  (e.g., see
> >> <https://github.com/usc-isi/nova/blob/hpc-testing/nova/virt/libvirt/connection.py#L482>.
> >> But to be able to use lxc-attach, we had to upgrade the Linux kernel in
> >> RHEL6.1 from 2.6.32 to 2.6.38. This kernel isn't supported by SGI, which
> >> means that we aren't able to load the SGI numa-related kernel modules.

Can you clarify what you mean by volume attachment ?

Are you talking about passing through host block devices, or hotplug of
further filesystems for the container ?

> > Why not address these couple of issues in libvirt itself?

If you let me know what issues you have with libvirt + LXC in OpenStack,
I'll put them on my todo list.

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