[ovs-dev] question about revalidation

Ben Pfaff blp at nicira.com
Mon Mar 23 20:24:34 UTC 2015


On Wed, Mar 18, 2015 at 06:30:17PM +0000, Gray, Mark D wrote:
> In udpif_revalidator(), the leader thread seems to adjust the datapath flow_limit
> in response to duration (which is the time taken to revalidate). It does this with
> some heuristic calculations that I have reproduced below. Not sure exactly why it
> is doing this or how the heuristics work as I would have assumed the flow_limit would
> be independent of revalidation time. Can anyone shed some light on that for me?
> 
>             if (duration > 2000) {
>                 flow_limit /= duration / 1000;
>             } else if (duration > 1300) {
>                 flow_limit = flow_limit * 3 / 4;
>             } else if (duration < 1000 && n_flows > 2000
>                        && flow_limit < n_flows * 1000 / duration) {
>                 flow_limit += 1000;
>             }

The number of flows is limited so that OVS can be confident that it
can revalidate every flow within a bounded amount of time (I think the
goal is 1 second).



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