Toke Høiland-Jørgensen <[email protected]> writes: > Fabian Ruffy <[email protected]> writes: > >> Hello, >> >> this is a somewhat esoteric question. I am trying to actually force >> bufferbloat >> in an emulation setup I am using. I set up a dumbbell topology and push >> traffic >> through it, causing congestion at the central link. I use this setup to >> compare >> congestion avoidance algorithms such as DCTCP to other solutions. >> This has worked nicely with the 4.18 kernel. However, after upgrading to >> 4.19 I >> cannot reproduce bufferbloat anymore. The traffic (even UDP packets) is >> perfectly rate limited and I never see any congestion happening. This is >> great, >> but in practice it prevents me from prototyping algorithms. > > Ha, that's awesome! :D
I have not upgraded to this branch. And in general I do recomend using a separate box. "Nuke it from orbit, it's the only way to be *sure*". However, recently I was able to get bufferbloat by using network namespaces for my test, and perhaps that "still works"? In this extremely long thread there's a test setup of network namespaces you can try: https://github.com/systemd/systemd/issues/9725 > >> My interface configuration for bottlenecked links is: >> >> qdisc tbf 5: dev OBcbnsw1-eth2 root refcnt 2 rate 10Mbit burst 15000b lat >> 12.0ms >> Sent 6042 bytes 51 pkt (dropped 0, overlimits 0 requeues 0) >> backlog 0b 0p requeues 0 >> qdisc netem 10: dev OBcbnsw1-eth2 parent 5:1 limit 500 >> Sent 6042 bytes 51 pkt (dropped 0, overlimits 0 requeues 0) >> backlog 0b 0p requeues 0 >> >> >> I have the suspicion that it is related to the CAKE changes in the 4.19 >> kernel, >> but I am not exactly sure. I am not using tc cake at all. Do you maybe know >> what could cause this behavior? Apologies if this is the wrong mailing >> list. > > My guess would be changes in the TCP stack; can't point you to anything > specific off the top of my head, though... > > -Toke > _______________________________________________ > Cake mailing list > [email protected] > https://lists.bufferbloat.net/listinfo/cake _______________________________________________ Cake mailing list [email protected] https://lists.bufferbloat.net/listinfo/cake
