Public bug reported: This is a simple performance optimization bug. When creating multiple servers, if they are in an affinity group they are going to be on the same host. Or if simply the scheduler configuration is such that instances are packed onto as few hosts as possible rather than spread, the scheduler could return several of the same hosts for the list of instances being scheduled. We iterate over the instances and their selected hosts and we lookup the az for each host in the loop which is a query to the aggregates table in the API DB. If we have >1 of the same host in the list, we could optimize this by simply caching the host=az mapping.
https://github.com/openstack/nova/blob/4c37ff72e5446c835a48d569dd5a1416fcd36c71/nova/conductor/manager.py#L1263 ** Affects: nova Importance: Low Assignee: Matt Riedemann (mriedem) Status: Triaged ** Affects: nova/pike Importance: Low Status: Confirmed ** Affects: nova/queens Importance: Low Status: Confirmed ** Tags: conductor performance ** Also affects: nova/pike Importance: Undecided Status: New ** Also affects: nova/queens Importance: Undecided Status: New ** Changed in: nova/pike Status: New => Confirmed ** Changed in: nova/queens Status: New => Confirmed ** Changed in: nova/queens Importance: Undecided => Low ** Changed in: nova/pike Importance: Undecided => Low ** Changed in: nova Assignee: (unassigned) => Matt Riedemann (mriedem) -- You received this bug notification because you are a member of Yahoo! Engineering Team, which is subscribed to OpenStack Compute (nova). https://bugs.launchpad.net/bugs/1785327 Title: schedule_and_build_instances looks up host az for every instance even if using the same host Status in OpenStack Compute (nova): Triaged Status in OpenStack Compute (nova) pike series: Confirmed Status in OpenStack Compute (nova) queens series: Confirmed Bug description: This is a simple performance optimization bug. When creating multiple servers, if they are in an affinity group they are going to be on the same host. Or if simply the scheduler configuration is such that instances are packed onto as few hosts as possible rather than spread, the scheduler could return several of the same hosts for the list of instances being scheduled. We iterate over the instances and their selected hosts and we lookup the az for each host in the loop which is a query to the aggregates table in the API DB. If we have >1 of the same host in the list, we could optimize this by simply caching the host=az mapping. https://github.com/openstack/nova/blob/4c37ff72e5446c835a48d569dd5a1416fcd36c71/nova/conductor/manager.py#L1263 To manage notifications about this bug go to: https://bugs.launchpad.net/nova/+bug/1785327/+subscriptions -- Mailing list: https://launchpad.net/~yahoo-eng-team Post to : [email protected] Unsubscribe : https://launchpad.net/~yahoo-eng-team More help : https://help.launchpad.net/ListHelp
