[oslo.metrics][nova][oslo][oslo.messaging] oslo.metrics patch not working

I tried to backport this particular patch in order to add support for 'oslo.metrics' on openstack controller node first: https://github.com/openstack/oslo.messaging/commit/bdbb6d62ee20bfd5ffc59f877....

But it does not work. After adding the following configs in /etc/nova/nova.conf: [DEFAULT] default_log_levels = oslo.messaging=DEBUG [oslo_messaging_metrics] metrics_enabled = True

I could only see messages related to 'oslo.messaging._drivers' in nova log files, and there's nothing related to 'oslo.messaging._metrics', or any other ones under 'oslo.messaging'.

What else is needed for this back-ported patch to work on the controller?