1 // SPDX-License-Identifier: GPL-2.0
2 // Test of slow start after idle
3 // This test expects tso size to be at least initial cwnd * mss
4
5 `./defaults.sh
6 ./set_sysctls.py /proc/sys/net/ipv4/tcp_slow_start_after_idle=1 \
7 /proc/sys/net/ipv4/tcp_min_tso_segs=10`
8
9 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
10 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0
11 +0 bind(3, ..., ...) = 0
12 +0 listen(3, 1) = 0
13
14 +0 < S 0:0(0) win 65535 <mss 1000,sackOK,nop,nop,nop,wscale 7>
15 +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>
16 +.1 < . 1:1(0) ack 1 win 511
17 +0 accept(3, ..., ...) = 4
18 +0 setsockopt(4, SOL_SOCKET, SO_SNDBUF, [200000], 4) = 0
19
20 +0 write(4, ..., 26000) = 26000
21 +0 > P. 1:5001(5000) ack 1
22 +0 > P. 5001:10001(5000) ack 1
23 +0 %{ assert tcpi_snd_cwnd == 10, tcpi_snd_cwnd }%
24
25 +.1 < . 1:1(0) ack 10001 win 511
26 +0 %{ assert tcpi_snd_cwnd == 20, tcpi_snd_cwnd }%
27 +0 > P. 10001:20001(10000) ack 1
28 +0 > P. 20001:26001(6000) ack 1
29
30 +.1 < . 1:1(0) ack 26001 win 511
31 +0 %{ assert tcpi_snd_cwnd == 36, tcpi_snd_cwnd }%
32
33 +2 write(4, ..., 20000) = 20000
34 // If slow start after idle works properly, we should send 5 MSS here (cwnd/2)
35 +0 > P. 26001:31001(5000) ack 1
36 +0 %{ assert tcpi_snd_cwnd == 10, tcpi_snd_cwnd }%
37
38 // Reset sysctls
39 `/tmp/sysctl_restore_${PPID}.sh`
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