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1// SPDX-License-Identifier: GPL-2.02// Test of slow start when an outstanding flight of packets is3// less than the current cwnd, but still big enough that in slow4// 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) = 313 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 014 +0 bind(3, ..., ...) = 015 +0 listen(3, 1) = 016 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 25720 +0 accept(3, ..., ...) = 421 22// Only send 6 packets.23 +0 write(4, ..., 6000) = 600024 +0 > P. 1:6001(6000) ack 125 +0 %{ assert tcpi_snd_cwnd == 10, tcpi_snd_cwnd }%26 27 +0 < . 1:1(0) ack 2001 win 25728 +0 %{ assert tcpi_snd_cwnd == 12, 'cwnd=%d' % tcpi_snd_cwnd }%29 30 +0 < . 1:1(0) ack 4001 win 25731 +0 %{ assert tcpi_snd_cwnd == 12, 'cwnd=%d' % tcpi_snd_cwnd }%32 33 +0 < . 1:1(0) ack 6001 win 25734 +0 %{ assert tcpi_snd_cwnd == 12, 'cwnd=%d' % tcpi_snd_cwnd }%35