Description of problem: Now that placement is deployed, populated, and capable of answering more complex queries, we should utilize it to reduce the workload on the nova scheduler. The scheduler must filter large numbers of hosts down to very few during boot or migration actions, and is often the choke point for these operations. Specifically, the introduction of CellsV2 allows/requires deployments to have a single scheduler (or set of schedulers) for all of their compute hosts. Especially given the default limit of 1000 results from placement, the scheduler may not even be able to provide good answers to scheduling queries due to it asking overly vague questions of placement. We need a way to augment our queries to placement in order to receive smaller and more relevant sets of hosts from it, against which we apply our filters.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. https://access.redhat.com/errata/RHEA-2019:0045
The needinfo request[s] on this closed bug have been removed as they have been unresolved for 1000 days