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

Shawn Hartsock hartsocks at vmware.com
Fri Nov 1 15:20:17 UTC 2013

----- Original Message -----
> From: "Yunhong Jiang" <yunhong.jiang at intel.com>
> To: openstack-dev at lists.openstack.org
> Sent: Thursday, October 31, 2013 6:39:29 PM
> Subject: [openstack-dev] [nova][scheduler]The database access in the	scheduler filters
> 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.
> Thanks
> --jyh
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> OpenStack-dev at lists.openstack.org
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Sorry if I'm dumb, but please try to explain things to me. I don't think I follow...

10k nodes, 60 VM per node... is 600k VM in the whole cloud. A 3 hour life cycle for a VM means every hour 1/3 the nodes turn over so 200k VM  are created/deleted per hour ... divide by 60 for ... 3,333.333 per minute or ... divide by 60 for ... 55.5 VM creations/deletions per second ...

... did I do that math right? So where's the million DB accesses per second come from? Are the rules fired for every VM on every access so that 600k VM + 1 new VM means the rules fire 600k + 1 times? What? Sorry... really confused.

# Shawn Hartsock

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