vm will always pinned to numa node0 when numa_nodes=1 set

[guolei]

Description
===========

If flavor set metadata numa_nodes=1, but cpu_policy=dedicated not set, vm will always pinned to numa node0, which is the first node on host cells, and nume node1 never be used

such as:
if host have 2 numa node, flavor set numa_nodes=1, vm always pinned to numa node0
if host have 4 numa node, flavor set numa_nodes=2, vm always pinned to numa node0 and numa node1

we should keep cpu load balanced

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/759581

[shews (shews)]

hello, maybe use memory_usage to sort the host_cells is better? like host_cells = sorted(host_cells, key=lambda cell: cell.memory_usage)

[guolei (guolei-5)]

hi shews, it's a good idea. but if hw:mem_page_size is unset,cell.memory_usage maybe 0.
maybe we can consider both scenarios at the same time

[sean mooney (sean-k-mooney)]

please hold off and pushing addtional patches for this until after the ptg.
i have raised https://bugs.launchpad.net/nova/+bug/1893121 previouly to cover this more comprehensively but got pushback form some cores that this shoudl be treated as a feature not a bug.

i will be disucssing it at the ptg and if we decied to proceed i want to take the more complete approch considering instance, ram, cpus and pci devices i have propoesed in https://bugs.launchpad.net/nova/+bug/1893121