On Thu, 2017-10-05 at 23:52 +0200, Toke Høiland-Jørgensen wrote: > > > I think that's reasonable. I'm not really sure it's *necessary* > > though? Couldn't mac80211 return NULL, and then simply call > > wake_tx_queue again when the TXQ becomes eligible for scheduling > > again? Otherwise the driver might end up doing a lot of polling for > > it to become eligible again? > > Theoretically, but then there would have to be some kind of callback > or another mechanism to figure out when the queue is ready again. The > neat thing about DRR scheduling is that we just use the fact that > there was an attempt to schedule the queue as an opportunity to > increase that queue's deficit by one quantum. This does give a bit of > "polling overhead" as you say, but it has been hidden in the > measurement noise in all my tests.
Ok. > The obvious alternative is to do a token-based airtime scheduler, > where the airtime used by one station is immediately divided out to > all active stations. But that requires walking over all active > stations on every TX completion, and there's a lot of housekeeping to > make sure we don't accidentally starve everyone. So I'd prefer to > stick with the DRR scheduler :) Sure, works for me. I have no objection to defining a special error code (we can always use ERR_PTR(-EAGAIN) or something like that, after all) - we just need to be careful with driver updates. Given all these discussions, I'd actually like to put a temporary restriction on merging new drivers with TXQ support - Felix, I think you were planning to eventually use this for mt7601u? How far along is that? johannes
