'Populate neutron extension values for the instance.
If the extensions loaded contain QOS_QUEUE then pass the rxtx_factor.'

def _populate_neutron_extension_values(self, context, instance, pci_request_id, port_req_body, network=None, neutron=None, bind_host_id=None):

    self._refresh_neutron_extensions_cache(context, neutron=neutron)
    if (constants.QOS_QUEUE in self.extensions):
        flavor = instance.get_flavor()
        rxtx_factor = flavor.get('rxtx_factor')
        port_req_body['port']['rxtx_factor'] = rxtx_factor
    has_port_binding_extension = self._has_port_binding_extension(context, neutron=neutron)
    if has_port_binding_extension:
        port_req_body['port'][BINDING_HOST_ID] = bind_host_id
        self._populate_neutron_binding_profile(instance, pci_request_id, port_req_body)
    if (constants.DNS_INTEGRATION in self.extensions):
        if ((not has_port_binding_extension) or (not network.get('dns_domain'))):
            port_req_body['port']['dns_name'] = instance.hostname
