Comment 41 for bug 1670041

4.12 + the first change from https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1670041/comments/33 + 802.11ac network => looks better.

➜ linux git:(6f7da290413b) ✗ git --no-pager diff
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 4858e190f6ac..abcfecfb8bbe 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2102,7 +2102,7 @@ static bool tcp_small_queue_check(struct sock *sk, const struct sk_buff *skb,
 {
  unsigned int limit;

- limit = max(2 * skb->truesize, sk->sk_pacing_rate >> 10);
+ limit = max(4 * skb->truesize, sk->sk_pacing_rate >> 8);
  limit = min_t(u32, limit, sysctl_tcp_limit_output_bytes);
  limit <<= factor;

 uname -a
Linux blade 4.12.0-custom #1 SMP Fri Jul 14 02:49:01 MSK 2017 x86_64 x86_64 x86_64 GNU/Linux

iperf3 -c us
Connecting to host us, port 5201
[ 4] local 10.10.10.76 port 50346 connected to 10.10.10.30 port 5201
[ ID] Interval Transfer Bandwidth Retr Cwnd
[ 4] 0.00-1.00 sec 27.2 MBytes 228 Mbits/sec 0 215 KBytes
[ 4] 1.00-2.00 sec 32.2 MBytes 270 Mbits/sec 0 298 KBytes
[ 4] 2.00-3.00 sec 31.5 MBytes 265 Mbits/sec 0 397 KBytes
[ 4] 3.00-4.00 sec 31.8 MBytes 267 Mbits/sec 0 444 KBytes
[ 4] 4.00-5.00 sec 31.5 MBytes 265 Mbits/sec 0 444 KBytes
[ 4] 5.00-6.00 sec 31.5 MBytes 264 Mbits/sec 0 444 KBytes
[ 4] 6.00-7.00 sec 31.3 MBytes 263 Mbits/sec 0 444 KBytes
[ 4] 7.00-8.00 sec 31.5 MBytes 264 Mbits/sec 0 444 KBytes
[ 4] 8.00-9.00 sec 31.3 MBytes 262 Mbits/sec 0 444 KBytes
^C[ 4] 9.00-9.94 sec 29.3 MBytes 263 Mbits/sec 0 444 KBytes
- - - - - - - - - - - - - - - - - - - - - - - - -
[ ID] Interval Transfer Bandwidth Retr
[ 4] 0.00-9.94 sec 309 MBytes 261 Mbits/sec 0 sender
[ 4] 0.00-9.94 sec 0.00 Bytes 0.00 bits/sec receiver
iperf3: interrupt - the client has terminated