Re: adsl priority queueing

[Andre Lucas <lucas@ae-35.net>]

> using adsl you have a bandwidth of e.g. 100kbit up- und 800kbit
> downstream. the problem is: if you're up- and downloading at the same
> time the download rate drops also to about 100kbit because the ACKs are
> in the same queue as the upload packets, right?
> is there a obsd way to get the ACKs faster out of the box so the full
> 800kbit can be used??

I think that just about any scheduler apart from FIFO would see the slow
pipe being saturated by the bulk flow and would schedule the ACKs ahead
of it.

I don't think that even with FIFO the problem would be nearly as bad as
you suggest. You don't have to ACK every received segment, and TCP can
handle latency - otherwise you'd never get any performance out of (say)
transatlantic links.

And, of course, FIFO is just that. The ACKs will be inserted into the
stream at exactly the same rate, and (oversimplifying a little here) in
a given time period one less bulk packet would be transmitted to 'make
room' for the ACK. IMO it would work just like a little added latency.

If you're testing this, I'd love to see some real-world results.
 
Ta,
-Andre