Open Stack

On Wed, Oct 29, 2014 at 5:23 AM, Ihar Hrachyshka <ihrachys at 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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