ovs-vswitchd CPU usage is high and lots of "ip netns" stuck in "D" state

Issue

• Unable to reach dashboard / API for Openstack, all Instances are down. Incredibly small amounts of traffic get through now and again, but quickly go back down again.

• ovs-vswitchd is running incredibly high CPU (600-1100%).

• All three controllers have been standby and rebooted to begin to fix the issue but nothing improved the situation.