On Thu, Oct 27, 2016 at 10:57 AM, Yuchung Cheng <[email protected]> wrote: > On Thu, Oct 27, 2016 at 10:33 AM, Dave Taht <[email protected]> wrote: >> On Thu, Oct 27, 2016 at 10:04 AM, Steinar H. Gunderson >> <[email protected]> wrote: >>> On Fri, Oct 21, 2016 at 10:47:26AM +0200, Steinar H. Gunderson wrote: >>>> As a random data point, I tried a single flow from my main server in .no >>>> to my backup server in .nl and compared CUBIC (with sch_fq) to BBR >>>> (naturally >>>> also in sch_fq) on the sender side. The results were quite consistent >>>> across >>>> runs: >>> >>> Another datapoint: A friend of mine had a different, worse path (of about >>> 40 ms) >>> and tested with iperf. >>> >>> CUBIC delivered 20.1 Mbit/sec (highly varying). BBR delivered 485 Mbit/sec. >> >> I mostly live in a world (wifi) where loss is uncommon, unless forced >> on it with a AQM. >> >> At the moment my biggest beef with BBR is that it ignores ECN entirely >> (and yet negotiates it). BBR is then so efficient at using up all the >> pipe that a single queued aqm "marks madly" and everything else >> eventually starves. Watch "ping" fade out here... >> >> http://blog.cerowrt.org/flent/bbr-comprehensive/bbr_ecn_eventually_starving_ping.png > > Thanks Dave for this issue. We design BBR with CoDel in mind b/c Van > co-designs both :)
It works pretty darn good with codel without ecn. I'm pretty darn happy with it. fq_codel is even more lovely, especially when competing with cubic. There are issues with single queued aqms with BBR vs cubic http://blog.cerowrt.org/flent/bbr-ecncaps/bandwidth-share-creaming-cubic-flowblind-aqm.svg > We have tested BBR with CoDel before and it works. Well, against cubic on the same link in single queue mode, even without ecn, life looks like this: http://blog.cerowrt.org/flent/bbr-ecncaps/bandwidth-share-creaming-cubic-flowblind-aqm.svg but fq_codel is fine, so long as there is no ecn vs nonecn collission http://blog.cerowrt.org/flent/bbr-ecncaps/bandwidth-share-ecn-fq.png > Could you share your tcpdump traces with us (maybe > you already did but no sure) or suggest how to reproduce this. > > This is 2 bbr flow or bbr + ecn-cubic? (I am guessing based on caption > in your graph) That's two BBRs with ecn enabled, going through cake in the single queue aqm mode "flowblind". I have similar plots with pie and codel with ecn enabled somewhere. The emulation is 48ms RTT, 20Mbit down, 5Mbit up. Regrettably I'm on a couple deadlines (a talk tomorrow, and next thursday), and can't look harder, I do have caps comparing ecn vs noecn here http://blog.cerowrt.org/flent/bbr-ecncaps/ > >> >> somewhat conversely in fq_codel, this means that it ignores codel's >> marking attempts entirely and BBR retains it's own dynamics, (while >> the non-BBR flows are fine) which is kind of neat to watch. >> >>> /* Steinar */ >>> -- >>> Homepage: https://www.sesse.net/ >>> _______________________________________________ >>> Bloat mailing list >>> [email protected] >>> https://lists.bufferbloat.net/listinfo/bloat >> >> >> >> -- >> Dave Täht >> Let's go make home routers and wifi faster! With better software! >> http://blog.cerowrt.org >> _______________________________________________ >> Bloat mailing list >> [email protected] >> https://lists.bufferbloat.net/listinfo/bloat -- Dave Täht Let's go make home routers and wifi faster! With better software! http://blog.cerowrt.org _______________________________________________ Bloat mailing list [email protected] https://lists.bufferbloat.net/listinfo/bloat
