Comment 6 for bug 1789654

My working theory is that the ResourceTracker._copy_resources method is setting the ComputeNode.cpu_allocation_ratio (and other alloc ratios) to 0.0 based on config here:

https://github.com/openstack/nova/blob/f534495a427d1683bc536cf003ec02edbf6d8a45/nova/compute/resource_tracker.py#L622

And because of https://review.openstack.org/#/c/520024/ we are no longer calling ComputeNode.save() via ResourceTracker._update via ResourceTracker._init_compute_node so the ComputeNode.save() doesn't get called which would otherwise call ComputeNode._from_db_object which would fix the allocation ratio 0.0 values to the hard-coded defaults:

https://github.com/openstack/nova/blob/f534495a427d1683bc536cf003ec02edbf6d8a45/nova/objects/compute_node.py#L188

I've added more debug logging to the debug patch and will get another xenserver CI run.

Having said this, I'm not sure why this wouldn't be breaking us in the "normal" gate, i.e. tempest-full job.