Re: [PATCH RFC 2/2] batman-adv: Better half duplex penalty estimation

["Nicolas Escande" <nico.escande@gmail.com>]

On Wed Oct 18, 2023 at 9:58 PM CEST, Remi Pommarel wrote:
> [...]
> > 
> > Also, this seems to assume that time slices are divided equally.
> > That's probably only be true for WiFi drivers that have airtime
> > fairness changes integrated? So only recent versions of mt76,
> > ath9k and ath10k? Has anyone verified that this works fine not
> > only in AP but also in 11s mode?
>
> I don't know how that would behave on setup that does not have airtime
> fairness changes integrated, if you think the current dividing by two
> approach is better maybe this can be made a configurable option but that
> could be tricky ?

It seems to me that airtime fairness is something that most current drivers aim
at doing. Even the mac80211 scheduler is going this route with the itxq work.
So I feel like we should assume that with time, most drivers will be.
And devices that do not respect airtime fairness will probably not match the
current TP/2 rule either.

> [...]
> > 
> > And a third concern, but we'd probably have this issue with both
> > our current and your suggestion: Would we be off again 802.11be
> > and its "Multi-Link Operation" in the future?
>
> This, I have hard time figuring out how MLO would play along with
> B.A.T.M.A.N-Adv integration. Unfortunately right now I have no way
> to experiment that yet. IIUC the link would be a mix between half and
> full duplex, and this would probably complicate things a bit.
>
> Thanks a lot for your review.

For me MLO is hard to take into account. Depending on the drivers (and probably
on the firmwares mostly) we do not know if it is/will be used as a real
aggregation mechanism or as a way to have 'free' roaming between multiple bands.

Moreover, currently all the path throughput estimation is based on the expected
throuput that the 80211 stack gives us for individual sta. I beleive that very
few drivers actually provide a value for it.

So IMHO we should do our best to have a good path estimation based on the sta
estimated throughput, and it should be the mac80211 drivers job to provide us
with an accurate estimated throughput for each sta on a link. And yes in the MLO
case it will be a hard job indeed...