[Codel] BQL support in Ethernet drivers (and Kathie Nichols and Van Jacobson's new AQM, codel)

Dave Taht dave.taht at gmail.com
Mon May 21 21:29:52 EDT 2012


I would really like people to clearly mark when they are using pfifo_fast,
codel, and fq_codel.

Secondly, I note that for utterly best results it is useful to ALSO have
htb on on ingress to a value only slightly lower than the rate under
test, and fq_codel attached to
the bin(s)

(an example of this is in the deBloat repo on github - both ingress.sh
and simple_qos.sh)

It would be nice if doing ingress was as simple as egress, maybe using some sort
of tbf + fq_codel....

Otherwise for some benchmarks... at 100Mbit, you will see TCP_STREAM
behavior holding
the line at ~5ms, and TCP_MAERTS being in excess of 30ms, especially
when pfifo_fast is on the other
side. Or vice versa, depending on where you are running the test.

On Tue, May 22, 2012 at 2:22 AM, Rick Jones <rick.jones2 at hp.com> wrote:
> On 05/21/2012 04:30 PM, Rick Jones wrote:
>>
>> I think my original ones had the unfortunate effect of putting lines on
>> top of one another. Your's seem to put them pretty far apart (at least
>> sometimes). We aught to be able to find some reasonable medium in there
>> somewhere. I'm thinking if latency is the metric of greatest interest,
>> we want that to have the full y axis, and then the peak bandwidth of the
>> STREAM test be about half-way up?
>
>
> I've tweaked the bloat.sh script in a couple ways.  First, I changed how I
> compute the scaling factor, to implement what I described above. Second, I
> am using a negative value for the demo interval for the TCP_RR test.  This
> causes netperf to check if it is time to emit a result after each
> transaction rather than after what it thought would be the number of
> transactions in the interval.  In that way the latency line is much more
> robust in the face of a sudden bloating of the path.  The effect on
> transactions per second should be similar to that of enabling histograms.
>  An example of a test across my 100 Mbit/s link to a laptop is attached.
>
> happy benchmarking,
>
> rick jones
>
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-- 
Dave Täht
SKYPE: davetaht
US Tel: 1-239-829-5608
http://www.bufferbloat.net



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