Re: [PATCH v1 4/4] wifi: ath11k: report tx airtime and enable airtime fairness

Julius Bairaktaris <[email protected]> writes:

> mac80211's airtime scheduler charges sta->airtime[ac].deficit from one
> place, ieee80211_sta_register_airtime(). Unlike AQL there is no estimator
> fallback, and ath11k never calls it, so the ATF feature bit cannot be
> advertised on its own: the deficit would only ever be
> replenished, every station would stay permanently in credit, and the DRR
> would be inert. The bit is not a no-op in that state either, because it
> also moves txq insertion to the head of the active list, which
> __ieee80211_schedule_txq() documents as safe only because the DRR moves a
> station back once its deficit goes negative.
>
> fes_duration_us arrives with every PPDU's stats and is already
> accumulated into arsta->tx_duration a few lines above. Register it, and
> set the feature bit in the same change so the two cannot be separated.
>
> Measured on an IPQ8074 AP with two stations on one radio, a 1x1 VHT
> client at 433 Mbit/s and a 2x2 HE client, both receiving at once. Before,
> 'iw station set <mac> airtime_weight' is refused with -EOPNOTSUPP and the
> per-station airtime file reads zero. After, the weight is accepted and
> read back, TX airtime accumulates, and the per-AC deficits move.
>
> The fairness this delivers is coarse. Weighting the fast station 4:1 moves
> the slow station's share of airtime from 59.5% to 52.1% and the fast
> station's throughput from 315 to 392 Mbit/s: the direction is correct, the
> magnitude is not the ratio requested.

How consistent is this change between runs? Seems a bit marginal if the
policy was supposed to give a 4:1 ratio between stations, so does this
work at all?

-Toke