On Wed, Oct 29, 2014 at 5:23 AM, Ihar Hrachyshka <ihrachys@redhat.com> wrote:

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Hi all,

there is a series of Neutron backports in the Juno queue that are
intended to significantly improve service performance when handling
security groups (one of the issues that are main pain points of
current users):

- - https://review.openstack.org/130101
- - https://review.openstack.org/130098
- - https://review.openstack.org/130100
- - https://review.openstack.org/130097
- - https://review.openstack.org/130105

The first four patches are optimizing db side (controller), while the
last one is to avoid fetching security group rules by OVS agent when
firewall is disabled.

AFAIK we don't generally backport performance improvements unless they
are very significant (though I don't see anything written in stone
that says so), but knowing that those patches fix pain hotspots in
Neutron, and seem rather isolated, should we consider their inclusion?

Should we come up with some "official" rule on how we handle
performance enhancement backports?

I'm very much in favor of backporting known performance improvements, but in my experience, not all "performance improvements" actually improve performance, so I'd expect an appropriate benchmark to demonstrate a real performance benefit to coincide with the proposed patch.

For a hypothetical example, what seems like a clear cut improvement in review 130098 (remove unused columns from a query) *might* have an unforeseen side effect later on, where another component doesn't have the data it needs, so it suddenly starts issuing a new DB query to compensate. OpenStack is certainly complicated enough that it's impossible to make accurate assumptions about performance.

/Ihar
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