Johannes Berg <johannes@xxxxxxxxxxxxxxxx> writes: > On Tue, 2019-04-16 at 17:37 +0800, Herbert Xu wrote: >> On Tue, Apr 16, 2019 at 11:33:50AM +0200, Johannes Berg wrote: >> > On Tue, 2019-04-16 at 10:33 +0100, Toke Høiland-Jørgensen wrote: >> > > >> > > > It is true because we have an entire buffering layer in mac80211 (in >> > > > this case at least) and never push back to the stack. >> > > >> > > I'm wondering if we should be? >> > >> > I don't think so? We'd just buffer packets in yet another place. >> >> But you do realise that you're giving up on the rich queueing >> functionality that Linux provides (net/sched), > > Yes, that was a trade-off we always knew about. The model that Linux > provides is just not suited for wifi. As explained at great length here: https://www.usenix.org/conference/atc17/technical-sessions/presentation/hoilan-jorgesen (you already know that of course, Johannes) >> not to mention >> breaking certain applications that rely on congestion feedback? > > This I don't understand. The congestion feedback happens through socket > buffer space etc. which is still there (as long as nobody sneaks in an > skb_orphan() call) Sure, for TCP, the TSQ mechanism should keep the upper-level queue low as long as the SKBs are alive. But is this also the case for UDP? -Toke
