Hi Stuart, I had a similar sounding problem on CentOS running icehouse (ksoftirqd/0 at 100%, tcpdump showed GRE router advertisement flood). The workaround I found was to disable ipv6 by editing /etc/sysctl.conf. John Sent from my mobile device. ----- Reply message ----- From: "Stuart Fox" <stuart at demonware.net> To: "openstack-operators at lists.openstack.org" <openstack-operators at lists.openstack.org> Subject: [Openstack-operators] Neutron nf_conntrack performance Date: Sat, Aug 16, 2014 2:44 AM Hey other ops! Im having a serious problem with my neutron router getting spin locked in nf_conntrack_tuple_taken. Has anybody else experienced it? As the incoming request rate goes up, so nf_conntrack_tuple_taken runs very hot on CPU0 causing ksoftirqd/0 to run at 100%. At that point internal pings on the GRE network go sky high and its game over. Ubuntu 14.04/Icehouse 2014.1.1 on an ibm x3550 with 4 10G intel nics. eth0 - Mgt eth1 - GRE eth2 - Public eth3 - unused Any help very much appreciated! BR, Stuart -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.openstack.org/pipermail/openstack-operators/attachments/20140816/90ad70cd/attachment.html>