[Bloat] AQM creeping into L2 equipment

[Dave Taht]

I find it puzzling that you still lose the measurement flows early on. Setting
some QoS on via WTD might be interesting.

sub 2ms performance under this load is quite good.

If you have a later OS than 3.13 on the sources/sinks you might want
to try sch_fq (and sch_pfifo_fast for reference) - the improvements to
Linux's TCP are such that on a short path like this that the control
loop stays very tight - only two TSO offloads per flow, really
accurate use of tcp timestamps, etc.

See also if you have hardware flow control enabled (via ethtool)


On Thu, Mar 20, 2014 at 9:20 AM, Toke Høiland-Jørgensen <toke at toke.dk> wrote:
> Dave Taht <dave.taht at gmail.com> writes:
>
>> The standard test that I'm most interested in is the 2 ports into 1 topology:
>>
>> SOURCE
>>       |
>> SWITCH
>>  |            |
>> BOX1   BOX2
>
> Did a couple of tests of this with the default configuration of a Cisco
> WS-C2960X-24TD-L switch. Graphs and data files here:
>
> http://kau.toke.dk/experiments/cisco-switch/cisco-c2960x.html
>
> Conclusion: My test boxes need offloads and quite a bit of driver
> queueing to drive the 1Gbps link, which makes it difficult to say
> anything about the switch...
>
> Haven't fiddled with the QoS settings, but from what I can see they are
> rather limited, and takes a great deal of fiddling to setup (at least
> for someone who, like me, has pretty much zero experience with Cisco
> gear).
>
> If someone has suggestions for other switch configurations that would be
> worthwhile testing (as well as some help on how to configure it), I'll
> be happy to run the tests.
>
> -Toke



-- 
Dave Täht

Fixing bufferbloat with cerowrt: http://www.teklibre.com/cerowrt/subscribe.html