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

Russell Bryant rbryant at redhat.com
Sun Nov 3 13:02:18 UTC 2013

On 11/03/2013 03:12 PM, Russell Bryant wrote:
> 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
> implement.
> 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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