Ah..., the bitter bit of the reality sandwich. Yum :-(

But Dave's note about Felix's hook for per-station queueing makes it seem 
feasible, if only a lot of work.

Thanks, all, for the enlightenment!

Rich

On Aug 7, 2015, at 9:28 AM, Jonathan Morton <[email protected]> wrote:

> 
>> On 7 Aug, 2015, at 15:22, Rich Brown <[email protected]> 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
> 

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