[Bloat] "BBR" TCP patches submitted to linux kernel

[Yuchung Cheng]

On Thu, Oct 27, 2016 at 10:33 AM, Dave Taht <dave.taht at gmail.com> wrote:
> On Thu, Oct 27, 2016 at 10:04 AM, Steinar H. Gunderson
> <sgunderson at bigfoot.com> 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 :) We have tested BBR with CoDel before and it works.
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)

>
> 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/
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>
>
>
> --
> Dave Täht
> Let's go make home routers and wifi faster! With better software!
> http://blog.cerowrt.org
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