[Cerowrt-devel] FQ_Codel lwn draft article review

dpreed at reed.com dpreed at reed.com
Mon Nov 26 18:39:58 EST 2012

I'm not sure why people are focused on iperf as a test of fqcodel.
iperf is a "hot rod" test.   The UDP versions ignores congestion signals entirely, and thus is completely irrelevant to bufferbloat.
The TCP tests are focused on throughput only, in an extreme case.
While it might be a nice footnote in a discussion of bufferbloat mitigation to say that "iperf is not too badly affected", the purpose of iperf as a measurement tool has literally NOTHING to do with bufferbloat management.
In fact, the focus on optimizing iperf by a half a percent or so in laboratory conditions is *literally* how we ended up with bufferbloat in the first place.
You don't design a highly maneuverable jet fighter by designing a rocket that goes from point A to point B the fastest.
The Internet was NEVER supposed to support circuit switchable traffic models.
Someone needs to make a tool that measures the right thing - and using iperf is the opposite of the right thing.
-----Original Message-----
From: "Toke Høiland-Jørgensen" <toke at toke.dk>
Sent: Monday, November 26, 2012 6:21pm
To: "Dave Taht" <dave.taht at gmail.com>
Cc: "Paolo Valente" <paolo.valente at unimore.it>, "Eric Raymond" <esr at thyrsus.com>, codel at lists.bufferbloat.net, cerowrt-devel at lists.bufferbloat.net, "bloat" <bloat at lists.bufferbloat.net>, paulmck at linux.vnet.ibm.com, "David Woodhouse" <dwmw2 at infradead.org>, "John Crispin" <blogic at openwrt.org>
Subject: Re: [Cerowrt-devel] FQ_Codel lwn draft article review

Cerowrt-devel mailing list
Cerowrt-devel at lists.bufferbloat.net
Toke Høiland-Jørgensen <toke at toke.dk> writes:

> The latter should be pretty straight forward, I suppose. And if I recall
> correctly, you did want to measure the upstream jitter?

Following up on this, I've created a proof of concept python script that
starts an iperf server in the background, parses the output, and
presents a command line interface that dumps the parsed data in json
format when asked for a transfer ID (source port number).

The script is available here:

It should be pretty easy to make it listen to a socket instead and allow
clients to request 'their' data. If anyone thinks this will be useful,
I'll be happy to poke some more at it. :)


Toke Høiland-Jørgensen
toke at toke.dk
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.bufferbloat.net/pipermail/cerowrt-devel/attachments/20121126/b4e09248/attachment-0002.html>

More information about the Cerowrt-devel mailing list