Bug 1703198

Summary: networking-ovn calls to update_port take 6 seconds per call
Product: Red Hat OpenStack Reporter: Nate Johnston <njohnston>
Component: openstack-neutronAssignee: Slawek Kaplonski <skaplons>
Status: CLOSED CURRENTRELEASE QA Contact: Eran Kuris <ekuris>
Severity: high Docs Contact:
Priority: medium    
Version: 15.0 (Stein)CC: amuller, chrisw, dalvarez, michele, njohnston, scohen, twilson, vkommadi
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Last Closed: 2020-10-26 21:38:26 UTC Type: Bug
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Description Nate Johnston 2019-04-25 19:17:55 UTC 
The description of this bug is a synthesis of the information found in the email chain titled "Optimizing ML2 updates" between members of the Networking DFG on April 25, 2019.

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This bug is in the context of this BZ [0] which is now preventing
OpenShift to run on OpenStack with Kuryr (and it's fully supported!).

The main issue is that adding subports to a trunk results in
subsequent calls from networking-ovn to the ML2 plugin updating the
binding information of each subport to that of the parent [1]. Slaweq
measured this and it takes around 6 seconds. The difference between
OVN and OVS is that in OVS all happens in parallel processed by
different RPC workers while in OVN the processing is done serially.

Using a bulk update would not have helped much here. The problem is also that networking-ovn updates the port one by one (because the OVSDB events
that signal that a port transitioned to ACTIVE are processed serially).

We need to identify where those 6 seconds per call are being spent through profiling in order to asses if it is potentially optimizable.

[0] https://bugzilla.redhat.com/show_bug.cgi?id=1691044
[1] https://github.com/openstack/networking-ovn/blob/master/networking_ovn/ml2/mech_driver.py#L708
Comment 1 anil venkata 2019-04-26 07:26:40 UTC 
Daniel, you can use https://review.opendev.org/#/c/627414/ for profiling neutron server.