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 }%
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