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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, and not big enough to bump up cwnd.4//5// In this variant, the receiver ACKs every other packet,6// approximating standard delayed ACKs.7 8// Set up config.9`./defaults.sh`10 11 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 312 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 013 +0 bind(3, ..., ...) = 014 +0 listen(3, 1) = 015 16 +0 < S 0:0(0) win 32792 <mss 1000,sackOK,nop,nop,nop,wscale 7>17 +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8>18 +0 < . 1:1(0) ack 1 win 25719 +0 accept(3, ..., ...) = 420 21// Only send 5 packets.22 +0 write(4, ..., 5000) = 500023 +0 > P. 1:5001(5000) ack 124 +0 %{ assert tcpi_snd_cwnd == 10, tcpi_snd_cwnd }%25 26 +0 < . 1:1(0) ack 2001 win 25727 +0 %{ assert tcpi_snd_cwnd == 10, 'cwnd=%d' % tcpi_snd_cwnd }%28 29 +0 < . 1:1(0) ack 4001 win 25730 +0 %{ assert tcpi_snd_cwnd == 10, 'cwnd=%d' % tcpi_snd_cwnd }%31 32 +0 < . 1:1(0) ack 5001 win 25733 +0 %{ assert tcpi_snd_cwnd == 10, 'cwnd=%d' % tcpi_snd_cwnd }%34