[ovs-dev] [PATCH v2 ovn 0/3] ovn-controller: Logical flow processing optimizations

Dumitru Ceara dceara at redhat.com
Fri Aug 23 11:23:09 UTC 2019

This series adds some (independent) optimizations that improve
ovn-controller performance by lowering the number of operations that
need to be executed during a iteration of the main controller loop.

Each patch in the series addresses a bottleneck reported by running
`perf record -g --call-graph dwarf -i /usr/bin/ovn-controller` on a
system where the Southbound DB was already populated by ovn-northd.

The logical configuration of the OVN is:
- 500 logical routers
- 1 logical switch attached to each router
- 2 logical ports attached to each switch
- 4 ACLs per switch

To evaluate the performance impact of the change in a more realistic
way the following test is performed (on a single node that runs ovn-northd
and ovn-controller and emulates the VM hosts with OVS internal interfaces):
1. Start ovs-vswitchd.
2. Remove the Southbound DB such that ovn-northd needs to repopulate
   everything based on the Northbound DB contents.
3. Start a patched version of ovn-controller such that it tracks loop time
   execution information and how long it takes to process all logical flows
   from the Southbound DB.
4. At the same time with step 3 above, start ovn-northd which will populate
   the Southbound DB.

The following measurements are taken:
- real time (measured with `time`) to have all corresponding openflow flows
  processed by ovs-vswitchd.
- maximum ovn-controller main loop iteration duration
- average ovn-controller main loop iteration duration
- number of times ovn-controller executes the main loop until all logical
  flows are processed

Comparing the results before and after this series we see:
- 13% performance boost w.r.t. real time taken to have all openflow flows
  installed in ovs-vswitchd
- 41% decrease of average ovn-controller loop iteration duration and
  12% increase of ovn-controller number of loop iterations. Essentially
  processing loops are faster and can happen more often.
- 2% decrease of maximum ovn-controller main loop iteration duration.

Dumitru Ceara (3):
      ofctrl: Avoid recomputing match hash in ofctrl_dup_flow().
      ovn-controller: Optimize update of ct-zones external-ids.
      ovn-controller: Minimize SB DB port_binding lookups.

 controller/binding.c        |   19 ++++++++++++---
 controller/ofctrl.c         |    2 +-
 controller/ovn-controller.c |   53 +++++++++++++++++++++++++++++++++++++------
 controller/ovn-controller.h |   11 ++++++++-
 controller/physical.c       |    4 ++-
 controller/pinctrl.c        |   53 +++++++++++--------------------------------
 6 files changed, 87 insertions(+), 55 deletions(-)

v2: Send series for OVN repo instead of OVS.

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