Pete Heist <p...@heistp.net> writes: >> On Jan 5, 2019, at 2:35 PM, Toke Høiland-Jørgensen <t...@toke.dk> wrote: >> >> Pete Heist <p...@heistp.net> writes: >> >>>> On Jan 5, 2019, at 2:10 PM, Toke Høiland-Jørgensen <t...@toke.dk> wrote: >>>> >>>> Hmm, that's odd. Could you try adding this debugging line in >>>> adjust_parent_qlen(), right before the sch->q.qlen += n line: >>>> >>>> net_info_ratelimited("Adjusting parent qdisc %d with pkt += %d, >>>> len += %d", >>>> parentid, n, len); >>>> >>>> And see if you actually get any of those lines in your dmesg? >>> >>> I do see the messages twice, then not after that in the rest of the >>> output... >> >> Right. Looking at the HFSC code some more, I think the bug is actually >> caused by another, but related, interaction between HFSC and CAKE. >> >> Specifically, this line: >> >> https://elixir.bootlin.com/linux/v3.16.7/source/net/sched/sch_hfsc.c#L1605 >> >> where HFSC checks whether the child queue len is 1, which it interprets >> as the event that activates that queue. However, because CAKE splits the >> packet, this check will fail, and the HFSC class will not be activated. >> This also explains why you only see the bug with HFSC, and not with HTB >> (although I do think that we still need to update the hierarchy). >> >> The good news it that it is a fairly simple to fix in HFSC. The bad news >> is that it's something that's hard to work around from the out-of-tree >> CAKE... > > Aha, well, I wonder if we’ll see this problem with other qdiscs- maybe > cbq, if I ever get a chance to try it (not hurrying yet). Ideally this > interaction between qdiscs would be clarified somewhere, at some > point. :) > > Thanks a lot for doing the discovery though!
You're welcome, and thanks for you help :) > We may not have hfsc+cake with GSO splitting on older kernels very > soon, but what should we do with this? There’s nobody in MAINTAINERS > for hfsc, so we may not get much of a response to any bug > submissions... $ ./scripts/get_maintainer.pl net/sched/sch_hfsc.c Jamal Hadi Salim <j...@mojatatu.com> (maintainer:TC subsystem) Cong Wang <xiyou.wangc...@gmail.com> (maintainer:TC subsystem) Jiri Pirko <j...@resnulli.us> (maintainer:TC subsystem) "David S. Miller" <da...@davemloft.net> (maintainer:NETWORKING [GENERAL]) net...@vger.kernel.org (open list:TC subsystem) I'll submit a patch sometime next week, and also look into the qlen adjustment for CAKE GSO splitting... -Toke _______________________________________________ Cake mailing list Cake@lists.bufferbloat.net https://lists.bufferbloat.net/listinfo/cake