[openstack-dev] A simple way to improve nova scheduler

Boris Pavlovic boris at pavlovic.me
Wed Jul 24 19:12:44 UTC 2013

Hi Mike,

On Wed, Jul 24, 2013 at 1:01 AM, Mike Wilson <geekinutah at gmail.com> wrote:

> Again I can only speak for qpid, but it's not really a big load on the
> qpidd server itself. I think the issue is that the updates come in serially
> into each scheduler that you have running. We don't process those quickly
> enough for it to do any good, which is why the lookup from db. You can see
> this for yourself using the fake hypervisor, launch yourself a bunch of
> simulated nova-compute, launch a nova-scheduler on the same host and even
> with 1k or so you will notice the latency between the update being sent and
> the update actually meaning anything for the scheduler.
> I think a few points that have been brought up could mitigate this quite a
> bit. My personal view is the following:
> -Only update when you have to (ie. 10k nodes all sending update every
> periodic interval is heavy, only send when you have to)
> -Don't fanout to schedulers, update a single scheduler which in turn
> updates a shared store that is fast such as memcache
> I guess that effectively is what you are proposing with the added twist of
> the shared store.

Absolutely agree with this. Especially with using memcached (or redis) as
common storage for all schedulers.

Best regards,
Boris Pavlovic
Mirantis Inc.
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