Re: [RFC][PATCH] mac80211: Use PID controller for TX rate control

[Mattias Nissler <mattias.nissler@gmx.de>]

On Mon, 2007-12-03 at 12:54 +0100, Stefano Brivio wrote:
> On Mon, 03 Dec 2007 12:03:00 +0100
> Mattias Nissler <mattias.nissler@gmx.de> wrote:
> 
> > Wait a sec. Rate control is per station, so each AP will have it's own
> > rate control state.
> 
> Ah, right. So fixing the related TODO may make sense.

What TODO excactly are you talking about?

> 
> > Have you tried shorter sample intervals? Currently, it's once per
> > second. I plan to shorten it, maybe to 2Hz or even 4Hz and see whether
> > we can get better responsiveness and still stay stable. Also, the
> > integration time needs to be fine-tuned then.
> 
> Well, the integration and control times are just fine. I mean, you can tune
> them, but I wouldn't expect the result to be very different. I just think we
> need some intervention when exceptional events occur. But if you decide to
> fix that TODO, considering association an exceptional event wouldn't make
> sense any longer. I've seen improvements after interpolation cycles too,
> though.
> 
> > I also thought about your rate <-> failed frames table. I'm not
> > convinced this works, because I cannot see a way to obtain consistent
> > values for the table. Clearly, measuring table entries should be done
> > with equal interference conditions for all entries, and they must also
> > be adjusted over time. However, if we only collect data during normal
> > operation, we'll likely have good data only for the few recent rates we
> > were operating at.
> 
> Yes, that's exactly what I meant.

So? How to do it right?

Mattias