[ovs-dev] [PATCH] classifier: Skip tables if priorities guarantee no match.

[Ben Pfaff]

On Thu, Feb 07, 2013 at 10:04:14PM +0000, Rajahalme, Jarno (NSN - FI/Espoo) wrote:
> 
> On Feb 7, 2013, at 22:36 , ext Ben Pfaff wrote:
> 
> > With complicated flow tables and multiple levels of resubmit, I see
> > flow setup performance improvements of up to 5-6% with this patch.
> > 
> 
> I played around with the same issue last week and came up with a
> little bit different solution. I think I spotted couple more locations where
> the search can be stopped based on the max priority.
> 
> I'll send my patches right away. There are two parts:
> 
> 1. Maintain max priority of each table.
> 2. Maintain tables in descending priority order.
> 
> The latter should be beneficial e.g. for longest prefix match tables (such
> as an IP routing table that is implemented by assigning higher priorities
> for rules with longer prefixes) as tables with shorter prefixes need not be
> searched after a match is found.
> 
> I'd be interested to know how these perform with your test case, if you
> care to test. Anyway, please feel free use these as you see fit.

Your patch gives me close to a 15% improvement (versus the 5-6% I see
with my patch) and, furthermore, they move the classifier a direction
I was thinking about going anyway.  I'll review them with an eye
toward application.

Thanks a lot.

Ben