Comment 12 for bug 1665215

Reviewed: https://review.openstack.org/435633
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=958388fff0ae69ffb5b95639801c339744706c8e
Submitter: Jenkins
Branch: stable/ocata

commit 958388fff0ae69ffb5b95639801c339744706c8e
Author: Kevin Benton <email address hidden>
Date: Wed Feb 15 20:49:45 2017 -0800

    Skip native DHCP notifications on status change

    On profiling the get_devices_details communications between
    the agent and the server, a significant amount of time
    (60% in my dev env) is being spent in the AFTER_UPDATE events
    for the port updates resulting from the port status changes.

    One of the major offenders is the native DHCP agent notifier.
    On each port update it ends up retrieving the network for the
    port, the DHCP agents for the network, and the segments.

    This patch addresses this particular issue by adding logic to
    skip a DHCP notification if the only thing that changed on the
    port was the status. The DHCP agent doesn't do anything based on
    the status field so there is no need to update it when this is
    the only change.

    Change-Id: I948132924ec5021a9db78cf17efbba96b2500e8e
    Partial-Bug: #1665215
    (cherry picked from commit 840e04b6f122f022f67b600ed2f96ae5e92eabe0)