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

Boris Pavlovic boris at pavlovic.me
Mon Jul 22 14:43:43 UTC 2013


To get information about "all" compute nodes we should wait one periodic
task (60 seconds by default).
So starting will take a while.

But I don't think that this is a big problem:
1) if we are already able to wait each time for heavy and long (> few
seconds) db querie
2) if we have more then one scheduler, we are always able to turn and
change one by one.
(I don't think that having for 5 minutes old and new schedulers will break

Also as a first step that could be done to speed up scheduler:
We could just remove db.compute_node_get_all() and send RPC calls directly
to schedulers.
I think that patch-set that change this thing will be pretty small
(~100-150 lines of code) and doesn't requirers big changes in current
scheduler implementation.

Best regards,
Boris Pavlovic

Mirantis Inc.

On Mon, Jul 22, 2013 at 5:50 PM, Russell Bryant <rbryant at redhat.com> wrote:

> On 07/22/2013 08:16 AM, Boris Pavlovic wrote:
> >>> * How do you bring a new scheduler up in an existing deployment and
> make it get the full state of the system?
> >
> > You should wait for a one periodic task time. And you will get full
> > information about all compute nodes.
> This also affects upgrading a scheduler.  Also consider a continuous
> deployment setup.  Every time you update a scheduler, it's not usable
> for (periodic task interval) seconds/minutes?
> --
> Russell Bryant
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> OpenStack-dev at lists.openstack.org
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