[wallaby][nova] CPU topology and NUMA Nodes

Vikarna Tathe vikarnatathe at gmail.com
Fri Jun 25 05:39:49 UTC 2021


Hi Ammad,

It depends on your VM requirements. NUMA basically maps nic-mem-cpu. So if
the VM is high traffic catering, you should define the NUMA properties in
the flavor.

Vikarna

On Fri, 25 Jun 2021 at 10:34, Ammad Syed <syedammad83 at gmail.com> wrote:

> Hi,
>
> I am using openstack wallaby on ubuntu 20.04 and kvm. I am working to make
> optimized flavor properties that should provide optimal performance. I was
> reviewing the document below.
>
> https://docs.openstack.org/nova/wallaby/admin/cpu-topologies.html
>
> I have two socket AMD compute node. The workload running on nodes are
> mixed workload.
>
> My question is should I use default nova CPU topology and NUMA node that
> nova deploys instance by default OR should I use hw:cpu_sockets='2'
> and hw:numa_nodes='2'.
>
> Which one from above provide best instance performance ? or any other
> tuning should I do ?
>
> The note in the URL (CPU topology sesion) suggests that I should stay with
> default options that nova provides.
>
> Currently it also works with libvirt/QEMU driver but we don’t recommend it
> in production use cases. This is because vCPUs are actually running in one
> thread on host in qemu TCG (Tiny Code Generator), which is the backend for
> libvirt/QEMU driver. Work to enable full multi-threading support for TCG
> (a.k.a. MTTCG) is on going in QEMU community. Please see this MTTCG
> project <http://wiki.qemu.org/Features/tcg-multithread> page for detail.
>
>
> Ammad
>
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