Comment 12 for bug 1780348

Reviewed: https://review.openstack.org/639723
Committed: https://git.openstack.org/cgit/openstack/charm-neutron-openvswitch/commit/?id=00ca87fec3b59d24665c7db5886647ea9b2ca114
Submitter: Zuul
Branch: master

commit 00ca87fec3b59d24665c7db5886647ea9b2ca114
Author: Pete Vander Giessen <email address hidden>
Date: Wed Feb 27 17:04:19 2019 +0100

    Added gc_threshold overrides to sysctl.conf

    When clouds have a large number of hosts, the default size of the ARP
    cache is too small. The cache can overflow, which means that the
    system has no way to reach some ip addresses.

    Setting the threshold limits higher addresses the situation, in a
    reasonably safe way (the maximum impact is 5MB or so of additional RAM
    used). Docs on ARP at http://man7.org/linux/man-pages/man7/arp.7.html,
    and more discussion of the issue in the bug.

    Change-Id: I329ec51eff85a2a99a929c67ff0c68b3b36d7273
    Closes-Bug: 1780348