Re: [Cerowrt-devel] [Make-wifi-fast] [tsvwg] Comments on draft-szigeti-tsvwg-ieee-802-11e

[Jonathan Morton <chromatix99@gmail.com>]

> On 7 Aug, 2015, at 15:22, Rich Brown <richb.hanover@gmail.com> wrote:
> 
> - At that time, the wifi driver requests packets from fq_codel until a) the the fq_codel queues are empty, or b) the wifi frame is full. In either case, the wifi driver sends what it has.

There’s one big flaw with this: if packets are available for multiple destinations, fq_codel will generally give you a variety pack of packets for each of them.  But a wifi TXOP is for a single destination, so only some of the packets would be eligible for the same aggregate frame.

So what’s needed is a way for the wifi driver to tell the queue that it wants packets for the *same* destination as it’s transmitting to.

> - Once the transmit opportunity has come around, it's a matter of microseconds (I assume) to pull in a wifi frame's worth of packets from fq_codel

This is hard to guarantee in software in a general-purpose OS.

 - Jonathan Morton