diff options
Diffstat (limited to 'tools/testing/selftests/net/packetdrill/tcp_slow_start_slow-start-fq-ack-per-2pkt.pkt')
| -rw-r--r-- | tools/testing/selftests/net/packetdrill/tcp_slow_start_slow-start-fq-ack-per-2pkt.pkt | 63 |
1 files changed, 63 insertions, 0 deletions
diff --git a/tools/testing/selftests/net/packetdrill/tcp_slow_start_slow-start-fq-ack-per-2pkt.pkt b/tools/testing/selftests/net/packetdrill/tcp_slow_start_slow-start-fq-ack-per-2pkt.pkt new file mode 100644 index 000000000000..7e9c83d617c2 --- /dev/null +++ b/tools/testing/selftests/net/packetdrill/tcp_slow_start_slow-start-fq-ack-per-2pkt.pkt @@ -0,0 +1,63 @@ +// SPDX-License-Identifier: GPL-2.0 +// Test of slow start when not application-limited, so that +// the cwnd continues to grow, even if TSQ triggers. +// In this variant, the receiver ACKs every other packet, +// approximating standard delayed ACKs. + +// Note we use FQ/pacing to check if TCP Small Queues is not hurting + +`./defaults.sh +tc qdisc replace dev tun0 root fq +sysctl -q net/ipv4/tcp_pacing_ss_ratio=200 +sysctl -e -q net.ipv4.tcp_min_tso_segs=2` + + 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 + +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 + +0 bind(3, ..., ...) = 0 + +0 listen(3, 1) = 0 + + +.1 < S 0:0(0) win 32792 <mss 1460,sackOK,nop,nop,nop,wscale 7> + +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 8> + +.1 < . 1:1(0) ack 1 win 500 + +0 accept(3, ..., ...) = 4 + +0 setsockopt(4, SOL_SOCKET, SO_SNDBUF, [200000], 4) = 0 + + +0 write(4, ..., 40000) = 40000 +// This might change if we cook the initial packet with 10 MSS. + +0 > P. 1:2921(2920) ack 1 + +0 > P. 2921:5841(2920) ack 1 + +0 > P. 5841:8761(2920) ack 1 + +0 > P. 8761:11681(2920) ack 1 + +0 > P. 11681:14601(2920) ack 1 + +0 %{ assert tcpi_snd_cwnd == 10, tcpi_snd_cwnd }% + ++.105 < . 1:1(0) ack 2921 win 500 + +0 %{ assert tcpi_snd_cwnd == 12, tcpi_snd_cwnd }% + +// Note: after this commit : "net_sched: sch_fq: account for schedule/timers drifts" +// FQ notices that this packet missed the 'time to send next packet' computed +// when prior packet (11681:14601(2920)) was sent. +// So FQ will allow following packet to be sent a bit earlier (quantum/2) +// (FQ commit allows an application/cwnd limited flow to get at most quantum/2 extra credit) + +0 > P. 14601:17521(2920) ack 1 + ++.003 < . 1:1(0) ack 5841 win 500 + +0 %{ assert tcpi_snd_cwnd == 14, tcpi_snd_cwnd }% + ++.001 > P. 17521:20441(2920) ack 1 + ++.001 < . 1:1(0) ack 8761 win 500 + +0 %{ assert tcpi_snd_cwnd == 16, tcpi_snd_cwnd }% + +// remaining packets are delivered at a constant rate. ++.007 > P. 20441:23361(2920) ack 1 + ++.002 < . 1:1(0) ack 11681 win 500 + +0 %{ assert tcpi_snd_cwnd == 18, tcpi_snd_cwnd }% ++.001 < . 1:1(0) ack 14601 win 500 + ++.004 > P. 23361:26281(2920) ack 1 + ++.007 > P. 26281:29201(2920) ack 1 + + +0 %{ assert tcpi_snd_cwnd == 20, 'cwnd=%d' % tcpi_snd_cwnd }% |