[ovs-git] [ovn-org/ovn] 20a204: controller: Check for tunnel change in multi-vtep ...

[venuiyer]

  Branch: refs/heads/master
  Home:   https://github.com/ovn-org/ovn
  Commit: 20a20439219493f27eb222617f045ba54c95ebfc
      https://github.com/ovn-org/ovn/commit/20a20439219493f27eb222617f045ba54c95ebfc
  Author: venu iyer <venugopali at nvidia.com>
  Date:   2020-09-28 (Mon, 28 Sep 2020)

  Changed paths:
    M controller/chassis.c
    M tests/ovn.at

  Log Message:
  -----------
  controller: Check for tunnel change in multi-vtep case is incorrect

Prior to multi-vtep, there was one tunnel for each type, since
there was only one encap-ip. So, the check in
chassis_tunnels_changed():

    sset_count(encap_type_set) != encap_type_count

worked. However, with multiple IPs per tunnel type, the above
check won't work. So, once multiple encap-ips are configured,
ovn-controller will always keep updating the encap list in
the SB (due to the above check); this causes a lot of unnecessary
churn, including recomputing the flows etc. which will put
ovn-controller in overdrive thereby consuming lot of CPU cycles
(see almost 100%)

Verified ovn-controller cpu utilization with the fix (and also
that SB doesn't keep constantly updating). make check didn't
show any additional failures.

Fixes: Fixes: b520ca7 ("Support for multiple VTEP in OVN")
Signed-off-by: venu iyer <venugopali at nvidia.com>
Signed-off-by: Numan Siddique <numans at ovn.org>