[Cake] [Codel] Proposing COBALT

[Rick Jones]

On 05/20/2016 10:07 AM, Jonathan Morton wrote:
>
>> On 20 May, 2016, at 20:01, Rick Jones <rick.jones2 at hpe.com> wrote:
>>
>> But I haven't seen that EMSGSIZE happen with netperf UDP tests -
>> could be though I've never run them in an environment which
>> triggered PTMUD.
>
> It’s entirely possible that netperf and/or iperf3 are (ab)using the
> IP_MTU_DISCOVERY socket option mentioned.

I cannot speak to iperf, but netperf doesn't manipulate 
IP_MTU_DISCOVERY.  It will set IP_RECVERR for a UDP_STREAM test, and 
will by default set SO_DONTROUTE (*) for UDP_STREAM but no IP_MTU_DISCOVERY.

happy benchmarking,

rick jones

* QA engineers doing link up/down testing with UDP_STREAM on test 
systems not air-gapped from the production networks are dangerous 
creatures...