Re: [Make-wifi-fast] mesh deployment with ath9k driver changes

["Toke Høiland-Jørgensen" <toke@toke.dk>]

Pete Heist <pete@eventide.io> writes:

>> On Apr 24, 2018, at 4:34 PM, Toke Høiland-Jørgensen <toke@toke.dk> wrote:
>> 
>> Not sure. You do get HOL blocking while a packet is retried, basically.
>> And ath9k will keep trying way after it should have given up (up to 30
>> retries per packet). If you combine this with a lot of backoff for each
>> transmission (which is also quite likely in a very congested setting),
>> and I suppose it might be possible…
>
> So that means everyone else waits while a packet is sent and re-sent
> to a station with a weak signal, for example? I see how that would
> wreck the latency pretty quick with the number of stations connected,
> plus channel contention with another repeater. It may be a much bigger
> factor than bloat.

Yup, exactly...

> The physical situation is that there’s an AP on the roof of one cabin,
> and it’s surrounded by about 8 occupied cabins, each with 4 kids, at
> least one of which is probably curled up inside using Instagram or
> YouTube. Signals and tx bitrates of the stations are below, for
> interest. What I’ll try to find out is if it’s the activities of one
> or two devices that affect things the most, as it appears that mean
> latency can suddenly go down to < 10ms and up to > 200ms because of
> “something"...

Yeah, with those signal rates, there's going to be quite some pause when
the slow stations try to transmit something... :/

-Toke