---
upgrade:
  - |
    Support for custom scheduler drivers, deprecated since the 21.0.0 (Ussuri)
    release, has been removed. The default ``filter_scheduler`` is now
    considered performant enough to suit all use cases. Users with specific
    requirements that they feel are not met by the filter scheduler should
    contact the nova developers to discuss their issue.
  - |
    The ``[scheduler] scheduler_driver`` config option has been removed, along
    with the ``nova.scheduler.driver`` setuptools entrypoint.
  - |
    The ``[scheduler] periodic_task_interval`` config option has been removed.
    It was no longer used by any supported scheduler drivers.
