Hello Everyone, In one of the OVN deployments, we are seeing 100% CPU usage by ovn-controllers all the time.
After investigations we found the below - ovn-controller is taking more than 20 seconds to complete full loop (mainly in lflow_run() function) - The physical switch is sending GARPs periodically every 10 seconds. - There is ovn-bridge-mappings configured and these GARP packets reaches br-int via the patch port. - We have a flow in router pipeline which applies the action - put_arp if it is arp packet. - ovn-controller pinctrl thread receives these garps, stores the learnt mac-ips in the 'put_mac_bindings' hmap and notifies the ovn-controller main thread by incrementing the seq no. - In the ovn-controller main thread, after lflow_run() finishes, pinctrl_wait() is called. This function calls - poll_immediate_wake() as 'put_mac_bindings' hmap is not empty. - This causes the ovn-controller poll_block() to not sleep at all and this repeats all the time resulting in 100% cpu usage. The deployment has OVS/OVN 2.9. We have back ported the pinctrl_thread patch. Some time back I had reported an issue about lflow_run() taking lot of time - https://mail.openvswitch.org/pipermail/ovs-dev/2019-July/360414.html I think we need to improve the logical processing sooner or later. But to fix this issue urgently, we are thinking of the below approach. - pinctrl_thread will locally cache the mac_binding entries (just like it caches the dns entries). (Please note pinctrl_thread can not access the SB DB IDL). - Upon receiving any arp packet (via the put_arp action), pinctrl_thread will check the local mac_binding cache and will only wake up the main ovn-controller thread only if the mac_binding update is required. This approach will solve the issue since the MAC sent by the physical switches will not change. So there is no need to wake up ovn-controller main thread. In the present master/2.12 these GARPs will not cause this 100% cpu loop issue because incremental processing will not recompute flows. Even though the above approach is not really required for master/2.12, I think it is still Ok to have this as there is no harm. I would like to know your comments and any concerns if any. Thanks Numan _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
