Comment 78 for bug 1813703

Reviewed: https://review.opendev.org/649693
Committed: https://git.openstack.org/cgit/openstack/neutron/commit/?id=bb2734b0d524aef348b69ae02988449f9dd63c56
Submitter: Zuul
Branch: stable/ocata

commit bb2734b0d524aef348b69ae02988449f9dd63c56
Author: LIU Yulong <email address hidden>
Date: Thu Feb 21 16:39:50 2019 +0800

    Do not call update_device_list in large sets

    Ovs-agent can process the ports in large sets, then all
    of these ports will have to update DB status or attributes.
    But neutron server is centralized. It may have to do
    something else, or the database processing can be also
    time-consuming. Because of these, it sometimes returns
    the RPC timeout exception to ovs-agent. And a fullsync
    will be triggered in next rpc loop. The restart time is
    becoming longer and longer.

    Adds a default step to update the port to reduce
    the probability of RPC timeout.

    Related-Bug: #1813703
    Related-Bug: #1813704
    Related-Bug: #1813706
    Related-Bug: #1813707

    Conflicts:
            neutron/common/constants.py
            neutron/agent/rpc.py
            neutron/tests/unit/plugins/ml2/test_rpc.py

    Change-Id: Ie37f4a4869969e235ce16b73cdfcbdc98626823e
    (cherry picked from commit 8408af4f173a0ffde354599e26c49bf9e17e8bef)