[openstack-dev] design question : green thread model

Johannes Erdfelt johannes at erdfelt.com
Wed Jan 28 17:24:52 UTC 2015

On Wed, Jan 28, 2015, murali reddy <muralimmreddy at gmail.com> wrote:
> On hosts with multi-core processors, it does not seem optimal to run a
> single service instance with just green thread. I understand that on
> controller node, we can run one or more nova services but still it does not
> seem to utilize multi-core processors.
> Is it not a nova scaling concern?

It certainly depends on the service.

nova-compute isn't CPU limited for instance, so utilizing multiple cores
isn't necessary.

nova-scheduler generally isn't CPU limited either in our usage (at
Rackspace), but we use cells and as a result, we run multiple independent
nova-scheduler services.

If you've seen some scaling problems, I know the Nova team is open to
reports. In some cases, patches wouldn't be hard to develop to start
multiple processes, but no one has ever reported a need beyond nova-api.


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