[Bloat] TCP BBR paper is now generally available

[Eric Dumazet]

On Sat, 2016-12-03 at 20:13 +0100, Steinar H. Gunderson wrote:
> On Sat, Dec 03, 2016 at 08:03:50AM -0500, Neal Cardwell wrote:
> > Thanks for the report, Steinar. This is the first report we've had
> > like this, but it would be interesting to find out what's going on.
> > 
> > Even if you don't have time to apply the patches Eric mentions, it
> > would be hugely useful if the next time you have a slow transfer like
> > that you could post a link to a tcpdump packet capture (headers only
> > is best, say -s 120). Ideally the trace would capture a whole
> > connection, so we can see the wscale on the SYN exchange.
> 
> I tried reproducing it now. I can't get as far down as 50 Mbit/sec,
> but it stopped around 100 Mbit/sec, still without any clear bottlenecks.
> cubic was just as bad, though.
> 
> I've taken two tcpdumps as requested; I can't reboot this server easily
> right now, unfortunately. They are:
> 
>   http://storage.sesse.net/bbr.pcap -- ssh+tar+gnupg
>   http://storage.sesse.net/bbr2.pcap -- wget between same hosts
> 
> /* Steinar */

Hi Steinar

Huge ACK decimation it seems.

11:13:28.762772 IP6 S > C: Flags [.], seq 777672:779100, ack 3432, win 179, options [nop,nop,TS val 3498278784 ecr 864447699], length 1428
11:13:28.763145 IP6 S > C: Flags [.], seq 779100:783384, ack 3432, win 179, options [nop,nop,TS val 3498278784 ecr 864447699], length 4284
11:13:28.763190 IP6 S > C: Flags [.], seq 783384:789096, ack 3432, win 179, options [nop,nop,TS val 3498278784 ecr 864447699], length 5712
11:13:28.763239 IP6 S > C: Flags [.], seq 789096:790524, ack 3432, win 179, options [nop,nop,TS val 3498278784 ecr 864447699], length 1428
11:13:28.763334 IP6 S > C: Flags [.], seq 790524:791952, ack 3432, win 179, options [nop,nop,TS val 3498278784 ecr 864447699], length 1428
11:13:28.764109 IP6 S > C: Flags [.], seq 791952:794808, ack 3432, win 179, options [nop,nop,TS val 3498278785 ecr 864447699], length 2856
11:13:28.764138 IP6 S > C: Flags [.], seq 794808:800520, ack 3432, win 179, options [nop,nop,TS val 3498278785 ecr 864447699], length 5712
11:13:28.764189 IP6 S > C: Flags [.], seq 800520:804804, ack 3432, win 179, options [nop,nop,TS val 3498278785 ecr 864447699], length 4284
11:13:28.764980 IP6 S > C: Flags [.], seq 804804:806232, ack 3432, win 179, options [nop,nop,TS val 3498278787 ecr 864447700], length 1428
11:13:28.765034 IP6 S > C: Flags [.], seq 806232:811944, ack 3432, win 179, options [nop,nop,TS val 3498278787 ecr 864447700], length 5712
11:13:28.765086 IP6 S > C: Flags [.], seq 811944:817656, ack 3432, win 179, options [nop,nop,TS val 3498278787 ecr 864447700], length 5712
11:13:28.765905 IP6 S > C: Flags [.], seq 817656:823368, ack 3432, win 179, options [nop,nop,TS val 3498278787 ecr 864447700], length 5712
11:13:28.765956 IP6 S > C: Flags [.], seq 823368:829080, ack 3432, win 179, options [nop,nop,TS val 3498278787 ecr 864447700], length 5712
11:13:28.766005 IP6 S > C: Flags [.], seq 829080:831936, ack 3432, win 179, options [nop,nop,TS val 3498278787 ecr 864447700], length 2856
11:13:28.766869 IP6 S > C: Flags [.], seq 831936:834792, ack 3460, win 179, options [nop,nop,TS val 3498278789 ecr 864447700], length 2856
11:13:28.766898 IP6 S > C: Flags [.], seq 834792:840504, ack 3460, win 179, options [nop,nop,TS val 3498278789 ecr 864447700], length 5712
11:13:28.766947 IP6 S > C: Flags [.], seq 840504:841932, ack 3460, win 179, options [nop,nop,TS val 3498278789 ecr 864447700], length 1428
11:13:28.766997 IP6 S > C: Flags [.], seq 841932:843360, ack 3460, win 179, options [nop,nop,TS val 3498278789 ecr 864447700], length 1428
11:13:28.767532 IP6 C > S: Flags [.], ack 783384, win 4106, options [nop,nop,TS val 864447710 ecr 3498278784], length 0
11:13:28.767541 IP6 C > S: Flags [.], ack 789096, win 4151, options [nop,nop,TS val 864447710 ecr 3498278784], length 0
11:13:28.767543 IP6 C > S: Flags [.], ack 791952, win 4173, options [nop,nop,TS val 864447710 ecr 3498278784], length 0
11:13:28.767544 IP6 C > S: Flags [.], ack 794808, win 4195, options [nop,nop,TS val 864447710 ecr 3498278785], length 0
11:13:28.767546 IP6 C > S: Flags [.], ack 800520, win 4240, options [nop,nop,TS val 864447710 ecr 3498278785], length 0
11:13:28.767547 IP6 C > S: Flags [.], ack 804804, win 4273, options [nop,nop,TS val 864447710 ecr 3498278785], length 0
11:13:28.767549 IP6 C > S: Flags [.], ack 811944, win 4329, options [nop,nop,TS val 864447710 ecr 3498278787], length 0
11:13:28.767550 IP6 C > S: Flags [.], ack 817656, win 4374, options [nop,nop,TS val 864447710 ecr 3498278787], length 0
11:13:28.767552 IP6 C > S: Flags [.], ack 823368, win 4418, options [nop,nop,TS val 864447711 ecr 3498278787], length 0
11:13:28.767553 IP6 C > S: Flags [.], ack 829080, win 4463, options [nop,nop,TS val 864447711 ecr 3498278787], length 0
11:13:28.767554 IP6 C > S: Flags [.], ack 831936, win 4485, options [nop,nop,TS val 864447711 ecr 3498278787], length 0
11:13:28.767556 IP6 C > S: Flags [.], ack 834792, win 4508, options [nop,nop,TS val 864447711 ecr 3498278789], length 0
11:13:28.767557 IP6 C > S: Flags [.], ack 840504, win 4552, options [nop,nop,TS val 864447711 ecr 3498278789], length 0
11:13:28.767559 IP6 C > S: Flags [.], ack 843360, win 4575, options [nop,nop,TS val 864447711 ecr 3498278789], length 0

Just to be clear,what is the kernel version at the sender ?

Thanks !