> No, but on tx_completion we could do something like this: > airtime = CB(skb)->tx_time ?: CB(skb)->tx_time_est; > ieee80211_report_airtime(sta, airtime); > That way, if the driver sets the tx_time field to something the firmware > reports, we'll use that, and otherwise we'd fall back to the estimate. > Of course, there would need to be a way for the driver to opt out of > this, for drivers that report out of band airtime like ath10k does :) I doubt that will work, unless firmware can do per frame airtime update in the skb. It is more likely that firmware provides out of band airtime update for a period of time, like an aggregation. That's the case for ath10k: https://patchwork.kernel.org/patch/10684689 Regarding handling frame for station enters power saving mode: > > >> Oh, right. Didn't know that could happen (I assumed those would be > >> flushed out or something). But if we're going to go with Kan's > >> suggestion of having per-station accounting as well as a global > >> accounting for the device, we could just subtract the station's > >> outstanding balance from the device total when it goes into powersave > >> mode, and add it back once it wakes up again. At least I think that > >> would work, no? > >Yes, I think that would work. > Great! Will incorporate that, then. I think that could work but things could be a bit more complicated. Not sure I fully understand the usage of airtime_weight_sum in [PATCH V3 1/4] mac80211: Switch to a virtual time-based airtime scheduler: in ieee80211_schedule_txq(): local->airtime_weight_sum[ac] += sta->airtime_weight; in ieee80211_sta_register_airtime(): weight_sum = local->airtime_weight_sum[ac] ?: sta->airtime_weight; local->airtime_v_t[ac] += airtime / weight_sum; sta->airtime[ac].v_t += airtime / sta->airtime_weight; in __ieee80211_unschedule_txq local->airtime_weight_sum[ac] -= sta->airtime_weight; I assume the purpose of airtime_weight_sum is to count station's virtual airtime proportional to the number of active stations for fairness. My concern is the per interface local->airtime_weight_sum[ac] get updated when packets are released from a txq to lower layer, but it doesn't mean the airtime will be consumed (packets get transmitted) shortly, due to events like station enter power save mode, so the weight_sum used in ieee80211_sta_register_airtime() maybe inaccurate. For architects using firmware/hardware offloading, firmware ultimately controls packet scheduling and has quite a lot of autonomy. The host driver's airtime_weight_sum may get out of sync with the number of active stations actually scheduled by firmware even without power saving events. Is this a correct understanding? I kind of think the original method of airtime accounting using deficit maybe more robust in this regard.
