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

Jiang, Yunhong yunhong.jiang at intel.com
Tue Nov 5 00:17:02 UTC 2013

I agree that this will have benefit , but how much the benefit is may highly depends on the type
of instance created. If most of the instance are normal instance w/o any special requirement, we will have no benefit at all.


> -----Original Message-----
> From: Russell Bryant [mailto:rbryant at redhat.com]
> Sent: Sunday, November 03, 2013 12:12 AM
> To: openstack-dev at lists.openstack.org
> Subject: Re: [openstack-dev] [nova][scheduler]The database access in the
> scheduler filters
> 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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