[ovs-dev] [PATCH] ovn: Avoid nb_cfg update notification flooding

[Ben Pfaff]

On Fri, Mar 16, 2018 at 02:31:49PM -0700, Han Zhou wrote:
> nb_cfg as a mechanism to "ping" OVN control plane is very useful
> in many ways. However, the current implementation will trigger
> update notifications flooding in the whole control plane. Each
> HV updates to SB the nb_cfg number and all these updates are
> notified to all the other HVs, which is O(n^2). Although updates
> are batched in fewers notifications than n^2, it still generates
> significant load on SB DB and also on ovn-controllers.
> 
> To solve this problem and make the mechanism more useful in large
> scale producation deployment, this patch separates the per HV
> nb_cfg data in SB from the Chassis table to a separate table, so
> that each HV can conditionally monitor and get updates only for
> its own record.
> 
> Signed-off-by: Han Zhou <hzhou8 at ebay.com>

By removing columns this will break upgrades.  Do you have another idea?