Back off a little when the load on the networker is high.

l3_agent_load_backoff.diff

diff --git a/neutron/agent/l3/agent.py b/neutron/agent/l3/agent.py
index 20d885fe8..603998dad 100644
--- a/neutron/agent/l3/agent.py
+++ b/neutron/agent/l3/agent.py
@@ -13,6 +13,7 @@
 #    under the License.
 #

+import os
 import eventlet
 import netaddr
 from neutron_lib import constants as lib_const
@@ -483,6 +484,10 @@ class L3NATAgent(ha.AgentMixin,

     def _process_router_update(self):
         for rp, update in self._queue.each_update_to_next_router():
+            if os.getloadavg()[0] > 30:
+                LOG.warn('Loadavg is higher than 30, sleep 30 seconds.')
+                eventlet.sleep(30)
+
             LOG.debug("Starting router update for %s, action %s, priority %s",
                       update.id, update.action, update.priority)
             if update.action == queue.PD_UPDATE: