[ovs-dev] [pre-async 5/8] nicira-ext: Separate nx_aggregate_stats_reply from ofp_aggregate_stats_reply.

[Ben Pfaff]

On Thu, May 26, 2011 at 05:27:46PM -0700, Justin Pettit wrote:
> On May 26, 2011, at 9:50 AM, Ben Pfaff wrote:
> 
> > On Thu, May 26, 2011 at 01:19:18AM -0700, Justin Pettit wrote:
> >> On May 24, 2011, at 4:25 PM, Ben Pfaff wrote:
> >> 
> >> This isn't directly related to this patch, but it's come up before
> >> that hardware vendors sometimes don't have sufficient counters for
> >> all flows or may not be able to simultaneously gather flow and byte
> >> counters.  For port counters, the OpenFlow 1.0 spec explicitly
> >> states that a value of -1 can be used for counters that aren't
> >> supported.  I'd suggest that we adopt the same convention for flow
> >> counters.  At the very least for our extended ones.  What do you
> >> think?  It would mostly be the WDP, er ofproto, integrator's job, so
> >> I believe it's only a matter of adding a comment to the description
> >> of the structures.
> > 
> > This sounds reasonable, but integrators never work with these OpenFlow
> > data structures directly, so this isn't the right place to notify
> > integrators.  (It is the right place to notify people who are working
> > with our extended data structures, I guess.)  The right place would be
> > the comment on rule_get_stats() in ofproto/private.h.
> 
> It probably makes sense to document in both places, since this is the only documentation we provide to users of our extensions.
> 
> > When we're aggregating flow statistics, what should be the sum of
> > "unknown" with a known value?
> 
> I'd say "unknown", -1.
> 
> > I'll make a note to add a patch for this somewhere.

I sent out a patch.