[ovs-discuss] High OpenFlow upcall RTTs introduced between 2.0 and 2.1?

[Ben Pfaff]

On Wed, Apr 30, 2014 at 04:49:49PM +0200, Christian Stigen Larsen wrote:
> 
> Ben Pfaff <blp at nicira.com>:
> >> RTTs were up from an average of 87 ms to 541 ms.
> > 
> > An RTT of 87 ms is very high to begin with.  What does mininet do that
> > could cause such a high RTT?
> 
> Fair point.  Honestly, I don't know, but perhaps I can ask on mininet-discuss.
> 
> I thought it was simply due to the Python controller.  Remember it gets all
> packets and has to send down a forward-command for each.
> 
> But yeah, 47 ms extra per packet is quite the overhead (the
> link-latency configuration is 40 ms).

After I wrote that, I reread your email and guessed that it came from
a trip to the controller (possibly multiple trips?).