Re: [aqm] References on AQM test results and fq_nocodel

[Toke Høiland-Jørgensen <[e-mail]>]

Simon Barber <[e-mail]> writes:

> One problem with fair queueing is that it can be gamed. By opening
> multiple flows you achieve unfair priority. Part of Codel or PIE's
> beauty is that they are blind to the traffic, only reacting to the
> externally visible characteristics. This stems from the question 'what
> is a flow?'. There is no easy answer to this question, so Codel and
> PIE intentionally avoid the question.

Sure, if we knew what the One True Queue Management Scheme that always
did the right thing was, we probably wouldn't be having this
conversation. :)

> Of course in many practical situations some simple assumptions about
> what a flow is do work, and in those situations fair queueing performs
> very well. It's important to keep in mind the limitations though. Fair
> queueing is not a panacea.

Well, my focus has primarily been "why does my internet suck so much and
what can I do to fix it". And for that (e.g. home type networks)
fq_codel is very close to a panacea.

I am well aware that there probably exists situations in which the
fq_codel assumptions do not hold up (and we do point out a couple in the
draft). However, I don't think I've ever seen someone actually
*demonstrate* (you know, with data) a scenario where fq_codel performs
worse than either Codel or PIE. If someone can point me to such a
demonstration I'll be happy to be proved wrong... :)

-Toke