Comment 0 for bug 1834484

The function [1], called during the port retrieval, is killing the performance. Although this code is needed for the BW aware scheduler (Nova-Neutron RFE), the high number of DB calls done inside this function is reducing the performance.

Instead of this, we propose:
- To publish inside the port DB object its own network qos policy, if any.
- Use it inside this function to retrieve only once, if needed, the QoS policy.

NOTE: the patches, if accepted, should be cherry-picked into Stein too.

[1] https://github.com/openstack/neutron/blob/stable/stein/neutron/services/qos/qos_plugin.py#L86