[Qos] ingress bandwidth limit by ovs is not accurate

According to Open vSwitch FAQ [1], max-rate value which is set for
all queues in qos is set as link speed in case when it is not specified.
This can lead to inaccurate ingress bandwidth limits in case when QoS is
applied e.g. directly on tapXXX port (which is "tun" interface type) and
configured bandwidth limit is higher than interface's link_speed.
This patch set max-rate parameter in qos's other_config table to not use
default value determined by Open vSwitch and to make rate limits more
accurate.

The modification is covered by functional tests in
https://github.com/openstack/neutron/blob/master/neutron/tests/
functional/agent/test_ovs_lib.py.

[1] http://docs.openvswitch.org/en/latest/faq/qos/

Change-Id: Id937216a724fbf776298efd11f74ac71056cfe06
Closes-Bug: #1730605
(cherry picked from commit c43317e380)

neutron/agent/common/ovs_lib.py

@@ -702,23 +702,30 @@ class OVSBridge(BaseOVS):
         return queue_uuid
 
     def _update_bw_limit_profile(self, txn, port_name, qos_uuid,
-                                 queue_uuid, queue_type):
+                                 queue_uuid, queue_type, qos_other_config):
         queues = {queue_type: queue_uuid}
         if qos_uuid:
             txn.add(self.ovsdb.db_set(
                 'QoS', qos_uuid, ('queues', queues)))
+            txn.add(self.ovsdb.db_set(
+                'QoS', qos_uuid, ('other_config', qos_other_config)))
         else:
             external_ids = {'id': port_name}
             qos_uuid = txn.add(
                 self.ovsdb.db_create(
-                    'QoS', external_ids=external_ids, type='linux-htb',
+                    'QoS', external_ids=external_ids,
-                    queues=queues))
+                    type='linux-htb',
+                    queues=queues,
+                    other_config=qos_other_config))
         return qos_uuid
 
     def update_ingress_bw_limit_for_port(self, port_name, max_kbps,
                                          max_burst_kbps):
         max_bw_in_bits = str(max_kbps * 1000)
         max_burst_in_bits = str(max_burst_kbps * 1000)
+        qos_other_config = {
+            'max-rate': max_bw_in_bits
+        }
         queue_other_config = {
             'max-rate': max_bw_in_bits,
             'burst': max_burst_in_bits,
@@ -734,7 +741,8 @@ class OVSBridge(BaseOVS):
             )
 
             qos_uuid = self._update_bw_limit_profile(
-                txn, port_name, qos_uuid, queue_uuid, QOS_DEFAULT_QUEUE
+                txn, port_name, qos_uuid, queue_uuid, QOS_DEFAULT_QUEUE,
+                qos_other_config
             )
 
             txn.add(self.ovsdb.db_set(
@@ -742,16 +750,35 @@ class OVSBridge(BaseOVS):
 
     def get_ingress_bw_limit_for_port(self, port_name):
         max_kbps = None
+        qos_max_kbps = None
+        queue_max_kbps = None
         max_burst_kbit = None
-        res = self.find_queue(port_name, QOS_DEFAULT_QUEUE)
+
-        if res:
+        qos_res = self.find_qos(port_name)
-            other_config = res['other_config']
+        if qos_res:
+            other_config = qos_res['other_config']
             max_bw_in_bits = other_config.get('max-rate')
             if max_bw_in_bits is not None:
-                max_kbps = int(max_bw_in_bits) / 1000
+                qos_max_kbps = int(max_bw_in_bits) / 1000
+
+        queue_res = self.find_queue(port_name, QOS_DEFAULT_QUEUE)
+        if queue_res:
+            other_config = queue_res['other_config']
+            max_bw_in_bits = other_config.get('max-rate')
+            if max_bw_in_bits is not None:
+                queue_max_kbps = int(max_bw_in_bits) / 1000
             max_burst_in_bits = other_config.get('burst')
             if max_burst_in_bits is not None:
                 max_burst_kbit = int(max_burst_in_bits) / 1000
+
+        if qos_max_kbps == queue_max_kbps:
+            max_kbps = qos_max_kbps
+        else:
+            LOG.warning("qos max-rate %(qos_max_kbps)s is not equal to "
+                        "queue max-rate %(queue_max_kbps)s",
+                        {'qos_max_kbps': qos_max_kbps,
+                         'queue_max_kbps': queue_max_kbps})
+
         return max_kbps, max_burst_kbit
 
     def delete_ingress_bw_limit_for_port(self, port_name):