[openstack-dev] [nova][scheduler]The database access in the scheduler filters

Russell Bryant rbryant at redhat.com
Sun Nov 3 07:12:24 UTC 2013

On 11/01/2013 06:39 AM, Jiang, Yunhong wrote:
> I noticed several filters (AggregateMultiTenancyIsoaltion, ram_filter, type_filter, AggregateInstanceExtraSpecsFilter) have DB access in the host_passes(). Some will even access for each invocation.
> Just curios if this is considered a performance issue? With a 10k nodes, 60 VM per node, and 3 hours VM life cycle cloud, it will have more than 1 million DB access per second. Not a small number IMHO.

On a somewhat related note, here's an idea that would be pretty easy to

What if we added some optional metadata to scheduler filters to let them
indicate where in the order of filters they should run?

The filters you're talking about here we would probably want to run
last.  Other filters that could potentially efficiently eliminate a
large number of hosts should be run first.

Russell Bryant

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