[ovs-dev] ovn-northd-ddlog scale issues

Ben Pfaff blp at ovn.org
Tue Jun 29 22:32:26 UTC 2021


On Mon, Jun 28, 2021 at 05:40:53PM +0200, Dumitru Ceara wrote:
> On 5/20/21 5:50 PM, Ben Pfaff wrote:
> > On Thu, May 20, 2021 at 05:06:26PM +0200, Dumitru Ceara wrote:
> >> On 4/7/21 6:49 PM, Ben Pfaff wrote:
> >>
> >> [...]
> >>
> >>>>
> >>>> Thanks!  I can download them now.  It's back on my to-do list.
> >>>
> >>> I can reproduce the problem now.  I haven't fixed it yet, but I did fix
> >>> a nasty performance problem in ovn-nbctl that became really apparent
> >>> when working with your databases:
> >>> https://mail.openvswitch.org/pipermail/ovs-dev/2021-April/381909.html
> >>
> >> I was wondering if you had a chance to look at this since.
> > 
> > I haven't kept going.  I consider my series that gives a 5x performance
> > improvement a kind of checkpoint along the way.  I assumed at first that
> > it would get reviewed quickly so I could move on to other things, but no
> > one has looked at it yet.
> > 
> 
> 
> Hi Ben,
> 
> Just a note, I've tried this again with ovn-northd-ddlog built from
> current OVN master branch, running against the same DBs:

I've identified the problem.  It's because of the ReachableLogicalRouter
relation, which holds all pairs of routers (A,B) such that a packet at
router A can transit switches and rotuers to arrive at router B.  This
is inherently O(n**2) and in this example n is about 8,000.

I'll fix it.


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