[Bloat] What is fairness, anyway? was: Re: finally... winning on wired!

[Eric Dumazet]

Le dimanche 05 février 2012 à 12:53 -0500, Justin McCann a écrit :

> I was thinking of suggesting this (delaying ACKs to avoid cwnd
> increase), but doesn't that simply increase the RTT and/or RTT
> variance, and basically do the same thing we're trying to avoid? I
> suppose you could delay a bit, and then drop some earlier ACKs in case
> the sender only increases cwnd per ACK (and not by the number of
> segments the ACK covers), but that per-ACK behavior just seems like a
> bug to me.

I dont think it has anything with delaying acks. Acks are immediately
sent as soon as the incoming packets are delivered to tcp stack.

Check my script, their is no filter on ACK at all.

ingress AQM delays delivering of packets of big flows, _if_ some other
flows are also present and want their part of the bandwidth.

Eventually SFQ drops packets from those big flows, and senders
automatically decrease their congestion window.

I use this kind of ingress AQM on production proxies and it actually
works.