> On 27 Sep, 2016, at 21:18, Dave Taht <[email protected]> wrote: > >> On Tue, Sep 27, 2016 at 10:52 AM, Jonathan Morton <[email protected]> >> wrote: >> >>> On 25 Sep, 2016, at 21:30, Dave Taht <[email protected]> wrote: >>> >>> Judging from me tearing apart how TCP BBR works (presently) with ecn, >>> it looks like we need to add the equivalent to fq_codel ce_threshold >>> behaviors as well. >> >> If I’m reading the legend correctly, you are setting ce_threshold to 1ms to >> get the better-controlled result. But that effectively disables the codel >> algorithm and turns it into a simple “mark all packets over 1ms sojourn” for >> ECN capable traffic, because it’s a tighter limit than codel’s target. >> That’s too aggressive for non-BBR traffic. > > Yes it is. :) However the consensus appears to be that ECN should be > an earlier signal than drop, and the work over on the tcp-prague list > centers around repurposing ECT(1) as more like a DCTCP multi-bit > signal.
My interpretation of the consensus is more subtle: we need a signal earlier than we currently do, and with a weaker meaning, but we still need the strong, later signal. I don’t think we should use CE for that; it has a long-established and widely-deployed meaning. We *can* use ECT(1), which is presently unused in practice. > I'm really not sure if what I've seen with ce_threshold is the > desired behavior, vs a vs BBR, thus far - but I'd like to see the > option for it enter cake. Before I even consider doing that, could you add a comparable run with the current version of cake to that graph? COBALT is not quite identical to Codel, and this looks like a case where one of the differences could be important. - Jonathan Morton _______________________________________________ Cake mailing list [email protected] https://lists.bufferbloat.net/listinfo/cake
