Open Stack

On 21-06-13 07:24, Kashyap Chamarthy wrote:
> On 06/20/2013 10:18 PM, Russell Bryant wrote:
>> On 06/20/2013 10:36 AM, Giorgio Franceschi wrote:
>>> Hello, I created a blueprint for the implementation of:
>>>
>>> A tool for pinning automatically each running virtual CPU to a physical
>>> one in the most efficient way, balancing load across sockets/cores and
>>> maximizing cache sharing/minimizing cache misses. Ideally able to be run
>>> on-demand, as a periodic job, or be triggered by events on the host (vm
>>> spawn/destroy).
>>>
>>> Find it at https://blueprints.launchpad.net/nova/+spec/auto-cpu-pinning
>>>
>>> Any inputappreciated!
>> I'm actually surprised to see a new tool for this kind of thing.
>>
>> Have you seen numad?
>
> And a related post by Dan Berrange (but on lower layers -- libvirt) which explains how to
> do vcpu pinning and control NUMA affinity --
> http://berrange.com/posts/2010/02/12/controlling-guest-cpu-numa-affinity-in-libvirt-with-qemu-kvm-xen/
>
>
>
>
Yes Kashyap, thanks for the link, I had read that article while
researching the problem. It addresses the same issues, but the solution
is based on install-time, static configuration. We want something
requiring as little config as possible and able to allocate VMs at
runtime. Basically, what the author suggests in section "Fine tuning CPU
affinity at runtime", but automated for large-scale, hands-off environments.

Russell, thanks for your suggestion, I did not know of numad. It looks
interesting, but the way I understand it, it is a system-wide
NUMA-binding daemon without any configuration options or fine-tuning
capabilities. We want something that only deals with relevant kvm
processes, not all processes on the system, and also we would like to
make it configurable so that VM can advertise their "pinnability",
because sometimes you might not want all running domains on a host to be
treated the same. This is planned for a future release. Would numad be
suited to this task, in your opinion? I suppose one could use it as a
querying tool, with the -w switch, and apply its suggestions
selectively. Then, it would basically replace the strategy-making part
of pinhead. I will investigate this shortly.

Thanks everyone for your help, any further input much appreciated!
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