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

[Toke Høiland-Jørgensen <[e-mail]>]

"De Schepper, Koen (Koen)" <[e-mail]> writes:

> Reporting the self inflicted delay on greedy flows might be a good
> measurement to additionally report in the test suites, so its impact
> on greedy interactive applications can be estimated.

Some sort of greedy real-time media or equivalent is definitely missing
from my suite of tests. However, that is partly due to the lack of a
good tool to do it with; preferably one that actually matches real
deployed applications (webrtc for instance), and that doesn't require
either synchronised clocks, packet dumps, or inspecting the router
queues while running.

On the page I linked to there are packet dumps available from my tests,
btw, in case anyone does want to go extract some of these figures from
them...

> I expect also that the advantage of FQ in general will becomes less
> relevant if the queue of all flows in the network are very small and
> even most of the time empty. This is what you see already when a low
> latency configured AQM is combined with FQ. The lower the latency in
> the queues the less the impact of FQ. FQ might still have an advantage
> in case of dynamics where a queue build up cannot be avoided.

Well, I haven't yet seen an AQM that can keep the queue "very small and
even most of the time empty" in the presence of (e.g.) the RRUL test.
Especially not during the period where the flows start up (or, roughly
equivalent, if the bandwidth changes very rapidly). FQ helps a lot here,
especially for the transients.

-Toke