Comment 51 for bug 1670041

4.13-rc2 + tcp_output.c

- limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10);
+ limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 7);

w/ cubic

% iperf3 -c dest
Connecting to host dest, port 5201
[ 4] local src port 47742 connected to dest port 5201
[ ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 9.16 MBytes 76.8 Mbits/sec 0 218 KBytes
[ 4] 1.00-2.00 sec 10.4 MBytes 87.5 Mbits/sec 0 286 KBytes
[ 4] 2.00-3.00 sec 9.72 MBytes 81.5 Mbits/sec 0 301 KBytes
[ 4] 3.00-4.00 sec 9.95 MBytes 83.5 Mbits/sec 0 301 KBytes
[ 4] 4.00-5.00 sec 9.70 MBytes 81.3 Mbits/sec 0 301 KBytes
[ 4] 5.00-6.00 sec 9.77 MBytes 81.9 Mbits/sec 0 301 KBytes
[ 4] 6.00-7.00 sec 10.2 MBytes 85.6 Mbits/sec 0 301 KBytes
[ 4] 7.00-8.00 sec 9.92 MBytes 83.2 Mbits/sec 0 301 KBytes
[ 4] 8.00-9.00 sec 10.0 MBytes 84.0 Mbits/sec 0 345 KBytes
[ 4] 9.00-10.00 sec 10.2 MBytes 85.6 Mbits/sec 0 345 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 99.1 MBytes 83.1 Mbits/sec 0 sender
[ 4] 0.00-10.00 sec 98.5 MBytes 82.6 Mbits/sec receiver

w/ bbr

iperf3 -c dest
Connecting to host dest, port 5201
[ 4] local src port 42308 connected to dest port 5201
[ ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 3.16 MBytes 26.5 Mbits/sec 0 11.3 KBytes
[ 4] 1.00-2.00 sec 2.58 MBytes 21.7 Mbits/sec 0 11.3 KBytes
[ 4] 2.00-3.00 sec 2.54 MBytes 21.3 Mbits/sec 0 11.3 KBytes
[ 4] 3.00-4.00 sec 2.68 MBytes 22.5 Mbits/sec 0 11.3 KBytes
[ 4] 4.00-5.00 sec 2.55 MBytes 21.4 Mbits/sec 0 11.3 KBytes
[ 4] 5.00-6.00 sec 2.53 MBytes 21.2 Mbits/sec 0 11.3 KBytes
[ 4] 6.00-7.00 sec 2.72 MBytes 22.8 Mbits/sec 0 14.1 KBytes
[ 4] 7.00-8.00 sec 2.88 MBytes 24.1 Mbits/sec 0 11.3 KBytes
[ 4] 8.00-9.00 sec 2.55 MBytes 21.4 Mbits/sec 0 11.3 KBytes
[ 4] 9.00-10.00 sec 2.86 MBytes 24.0 Mbits/sec 0 14.1 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-10.00 sec 27.1 MBytes 22.7 Mbits/sec 0 sender
[ 4] 0.00-10.00 sec 27.0 MBytes 22.6 Mbits/sec receiver

HTH