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

Justin Pettit jpettit at nicira.com
Fri May 27 00:27:46 UTC 2011


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.


Awesome.

--Justin





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