tcp_slow_start_slow-start-ack-per-2pkt-send-6pkt.pkt

 1// SPDX-License-Identifier: GPL-2.0
 2// Test of slow start when an outstanding flight of packets is
 3// less than the current cwnd, but still big enough that in slow
 4// start we want to increase our cwnd a little.
 5//
 6// In this variant, the receiver ACKs every other packet,
 7// approximating standard delayed ACKs.
 8
 9// Set up config.
10`./defaults.sh`
11
12    0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
13   +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
14   +0 bind(3, ..., ...) = 0
15   +0 listen(3, 1) = 0
16
17   +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>
18   +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
19   +0 < . 1:1(0) ack 1 win 257
20   +0 accept(3, ..., ...) = 4
21
22// Only send 6 packets.
23   +0 write(4, ..., 6000) = 6000
24   +0 > P. 1:6001(6000) ack 1
25   +0 %{ assert tcpi_snd_cwnd == 10, tcpi_snd_cwnd }%
26
27   +0 < . 1:1(0) ack 2001 win 257
28   +0 %{ assert tcpi_snd_cwnd == 12, 'cwnd=%d' % tcpi_snd_cwnd }%
29
30   +0 < . 1:1(0) ack 4001 win 257
31   +0 %{ assert tcpi_snd_cwnd == 12, 'cwnd=%d' % tcpi_snd_cwnd }%
32
33   +0 < . 1:1(0) ack 6001 win 257
34   +0 %{ assert tcpi_snd_cwnd == 12, 'cwnd=%d' % tcpi_snd_cwnd }%