[openstack-dev] [keystone][performance][profiling] Profiling Mitaka Keystone: some results and asking for a help

Dina Belova dbelova at mirantis.com
Mon Apr 11 14:11:05 UTC 2016

Hey, openstackers!

Recently I was trying to profile Keystone (OpenStack Liberty vs Mitaka)
using this set of changes
currently on review - some final steps are required there to finish the
work) and OSprofiler.

Some preliminary results (all in one OpenStack node) can be found here
OSprofiler reports are not yet merged to some place and can be found here
<https://review.openstack.org/#/c/299514/>). The full plan
what's going to be tested  can be found in the docs as well. In short I
wanted to take a look how does Keystone changed its DB/Cache usage from
Liberty to Mitaka, keeping in mind that there were several changes

   - federation support was added (and made DB scheme a bit more complex)
   - Keystone moved to oslo.cache usage
   - local context cache was introduced during Mitaka

First of all - *good job on making Keystone less DB-extensive in case of
cache turned on*! If Keystone caching is turned on, number of DB queries
done to Keystone DB in Mitaka is averagely twice less than in Liberty,
comparing the same requests and topologies. Thanks Keystone community to
make it happen :)

Although, I faced *two strange issues* during my experiments, and I'm
kindly asking you, folks, to help me here:

   - I've created #1567403
   <https://bugs.launchpad.net/keystone/+bug/1567403> bug to share
   information - when I turned caching on, local context cache should cache
   identical per API requests function calls not to ping Memcache too often.
   Although I faced such calls, Keystone still used Memcache to gather this
   information. May someone take a look on this and help me figure out what am
   I observing? At the first sight local context cache should work ok, but for
   some reason I do not see it's being used.
   - One more filed bug - #1567413
   <https://bugs.launchpad.net/keystone/+bug/1567413> - is about a bit
   opposite situation :) When I turned cache off explicitly in the
   keystone.conf file, I still observed some of the values being fetched from
   Memcache... Your help is very appreciated!

Thanks in advance and sorry for a long email :)

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