[ovs-dev] [PATCH 0/3] OVN: add Controller Events

Lorenzo Bianconi lorenzo.bianconi at redhat.com
Wed Jul 10 17:07:34 UTC 2019

> On Fri, Jun 14, 2019 at 05:53:20PM +0200, Lorenzo Bianconi wrote:
> > The series here introduces a new table, Controller_Event, for this
> > purpose. Traffic into OVS can raise a controller() event that results in
> > a Controller_Event being written to the southbound database. The
> > intention is for a CMS to see the events and take some sort of action.
> > The "handled" column of the event is initially set to "false" by OVN.
> > When the CMS has seen the event and taken appropriate action, then the
> > CMS sets this field to "true'. When ovn-controller sees that the event
> > has been handled, it deletes the event from the database.
> > 
> > Controller events are only added to the southbound database if they have
> > been enabled in the nb_global table via the options:controller_event
> > setting.
> The above paragraphs of high-level information are helpful, but they are
> only in email and do not appear in the documentation.  I suggest adding
> them to the documentation so that the reader can see the whole picture.
> Some other high-level design comments:
> - I don't see an explanation of the sequence number and how it's used in
>   practice.
> - I don't yet understand why it's better to have the CMS set 'handled'
>   and then have ovn-controller delete the row, than to have the CMS
>   delete the row directly.

Hi Ben,

thx for the review.
I think controlling 'handled' field in a single point make the system more robust
against races but we can just move the control to the CMS.
I will post a v2 soon.


> - The passive voice in the second paragraph above makes it ambiguous who
>   sets options:controller_event.  I think that the CMS sets this; it
>   would be best for the documentation to say so.
> Thanks,
> Ben.

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