diff options
| author | Alice Mikityanska <alice@isovalent.com> | 2026-08-22 15:03:08 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-08-27 08:42:28 -0700 |
| commit | 1d62b83fb75125344693db8ebf970653db529f40 (patch) | |
| tree | b2562439718f723a8edc3c9e1c80ecdd868b2fdf | |
| parent | f7d0400bd3452ed6915592b1929ba1d39d8e6552 (diff) | |
selftests: net: Fix slow configurations in big_tcp_tunnels.sh
The combination of checksum offload disabled (that causes software GSO)
and a debug kernel is inherently slow. Depending on the CPU power and
load, RTT may increase, limiting sk_pacing_rate, so tcp_tso_autosize
caps SKBs at around 40 segments, and zero BIG TCP packets are produced.
Increase sysctl net.ipv4.tcp_min_tso_segs and set a bigger initial value
of CWND in these configurations to force BIG TCP.
Fixes: 5cb53743e1ff ("selftests: net: Add a test for BIG TCP in UDP tunnels")
Signed-off-by: Alice Mikityanska <alice@isovalent.com>
Acked-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
Link: https://patch.msgid.link/20260822120308.1165200-5-alice.kernel@fastmail.im
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
| -rwxr-xr-x | tools/testing/selftests/net/big_tcp_tunnels.sh | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/tools/testing/selftests/net/big_tcp_tunnels.sh b/tools/testing/selftests/net/big_tcp_tunnels.sh index 003878df7415..cc0875e52fb9 100755 --- a/tools/testing/selftests/net/big_tcp_tunnels.sh +++ b/tools/testing/selftests/net/big_tcp_tunnels.sh @@ -49,6 +49,8 @@ setup() { ip netns exec "$SERVER_NS" netserver >/dev/null wait_local_port_listen "$SERVER_NS" 12865 tcp + + DEFAULT_TCP_MIN_TSO_SEGS=$(ip netns exec "$CLIENT_NS" sysctl -n net.ipv4.tcp_min_tso_segs) } setup_tunnel() { @@ -135,6 +137,21 @@ do_test() { IPTABLES_SACK=ip6tables fi + if [ "$3" != 'on' ] && [ "$KSFT_MACHINE_SLOW" = yes ]; then + echo 'Slow configuration; increasing net.ipv4.tcp_min_tso_segs and initcwnd' + ip netns exec "$CLIENT_NS" sysctl -w net.ipv4.tcp_min_tso_segs=52 + if [ "$2" = 4 ]; then + ip -netns "$CLIENT_NS" \ + route change 192.168.2.0/24 dev tun0 initcwnd 100 + else + ip -netns "$CLIENT_NS" -6 \ + route change 2001:db8::2:0/112 dev tun0 initcwnd 100 + fi + else + ip netns exec "$CLIENT_NS" \ + sysctl -w net.ipv4.tcp_min_tso_segs="$DEFAULT_TCP_MIN_TSO_SEGS" + fi + ip netns exec "$SERVER_NS" "$IPTABLES" -w -t raw -I PREROUTING -i "${CAPTURE_IFACE}1" -m length ! --length 0:65535 -m comment --comment "bigtcp" ip netns exec "$CLIENT_NS" "$IPTABLES" -w -t raw -I OUTPUT -o "${CAPTURE_IFACE}0" -m length ! --length 0:65535 -m comment --comment "bigtcp" ip netns exec "$SERVER_NS" "$IPTABLES_SACK" -w -t raw -I OUTPUT -o "tun1" -p tcp -m tcp --tcp-flags ACK ACK --tcp-option 5 -m comment --comment "sack" |