Comment 3 for bug 1940668

Reviewed: https://review.opendev.org/c/openstack/nova/+/805649
Committed: https://opendev.org/openstack/nova/commit/d13412648d011994a146dac1e7214ead3b82b31b
Submitter: "Zuul (22348)"
Branch: master

commit d13412648d011994a146dac1e7214ead3b82b31b
Author: Ilya Popov <email address hidden>
Date: Mon Aug 23 16:44:25 2021 +0300

    Fix to implement 'pack' or 'spread' VM's NUMA cells

    Cells mean NUMA cells below in text.

    By default, first instance's cell are placed to the host's cell with
    id 0, so it will be exhausted first. Than host's cell with id 1 will
    be used and exhausted. It will lead to error placing instance with
    number of cells in NUMA topology equal to host's cells number if
    some instances with one cell topology are placed on cell with id 0
    before. Fix will perform several sorts to put less used cells at
    the beginning of host_cells list based on PCI devices, memory and
    cpu usage when packing_host_numa_cells_allocation_strategy is set
    to False (so called 'spread strategy'), or will try to place all
    VM's cell to the same host's cell untill it will be completely
    exhausted and only after will start to use next available host's
    cell (so called 'pack strategy'), when the configuration option
    packing_host_numa_cells_allocation_strategy is set to True.

    Partial-Bug: #1940668
    Change-Id: I03c4db3c36a780aac19841b750ff59acd3572ec6