Re: [PATCH net-next 3/3] selftests: drv-net: add a simple TSO test

Stanislav Fomichev
2025-02-13T02:49:40Z

On 02/12, Jakub Kicinski wrote:
> Add a simple test for TSO. Send a few MB of data and check device
> stats to verify that the device was performing segmentation.
> Do the same thing over a few tunnel types.
>
> Injecting GSO packets directly would give us more ability to test
> corner cases, but perhaps starting simple is good enough?
>
> # ./ksft-net-drv/drivers/net/hw/tso.py
> # Detected qstat for LSO wire-packets
> KTAP version 1
> 1..14
> ok 1 tso.ipv4 # SKIP Test requires IPv4 connectivity
> ok 2 tso.vxlan4_ipv4 # SKIP Test requires IPv4 connectivity
> ok 3 tso.vxlan6_ipv4 # SKIP Test requires IPv4 connectivity
> ok 4 tso.vxlan_csum4_ipv4 # SKIP Test requires IPv4 connectivity
> ok 5 tso.vxlan_csum6_ipv4 # SKIP Test requires IPv4 connectivity
> ok 6 tso.gre4_ipv4 # SKIP Test requires IPv4 connectivity
> ok 7 tso.gre6_ipv4 # SKIP Test requires IPv4 connectivity
> ok 8 tso.ipv6
> ok 9 tso.vxlan4_ipv6
> ok 10 tso.vxlan6_ipv6
> ok 11 tso.vxlan_csum4_ipv6
> ok 12 tso.vxlan_csum6_ipv6
> ok 13 tso.gre4_ipv6
> ok 14 tso.gre6_ipv6
> # Totals: pass:7 fail:0 xfail:0 xpass:0 skip:7 error:0
>
> Note that the test currently depends on the driver reporting
> the LSO count via qstat, which appears to be relatively rare
> (virtio, cisco/enic, sfc/efc; but virtio needs host support).
>
> Signed-off-by: Jakub Kicinski <kuba@kernel.org>
> ---
> .../testing/selftests/drivers/net/hw/Makefile | 1 +
> tools/testing/selftests/drivers/net/hw/tso.py | 226 ++++++++++++++++++
> 2 files changed, 227 insertions(+)
> create mode 100755 tools/testing/selftests/drivers/net/hw/tso.py
>
> diff --git a/tools/testing/selftests/drivers/net/hw/Makefile b/tools/testing/selftests/drivers/net/hw/Makefile
> index 21ba64ce1e34..ae783e18be83 100644
> --- a/tools/testing/selftests/drivers/net/hw/Makefile
> +++ b/tools/testing/selftests/drivers/net/hw/Makefile
> @@ -15,6 +15,7 @@ TEST_PROGS = \
> nic_performance.py \
> pp_alloc_fail.py \
> rss_ctx.py \
> + tso.py \
> #
>
> TEST_FILES := \
> diff --git a/tools/testing/selftests/drivers/net/hw/tso.py b/tools/testing/selftests/drivers/net/hw/tso.py
> new file mode 100755
> index 000000000000..ee3e207d85b3
> --- /dev/null
> +++ b/tools/testing/selftests/drivers/net/hw/tso.py
> @@ -0,0 +1,226 @@
> +#!/usr/bin/env python3
> +# SPDX-License-Identifier: GPL-2.0
> +
> +"""Run the tools/testing/selftests/net/csum testsuite."""
> +
> +import fcntl
> +import socket
> +import struct
> +import termios
> +import time
> +
> +from lib.py import ksft_pr, ksft_run, ksft_exit, KsftSkipEx, KsftXfailEx
> +from lib.py import ksft_eq, ksft_ge, ksft_lt
> +from lib.py import EthtoolFamily, NetdevFamily, NetDrvEpEnv
> +from lib.py import bkg, cmd, defer, ethtool, ip, rand_port, wait_port_listen
> +
> +
> +def sock_wait_drain(sock, max_wait=1000):
> + """Wait for all pending write data on the socket to get ACKed."""
> + for _ in range(max_wait):
> + one = b'\0' * 4
> + outq = fcntl.ioctl(sock.fileno(), termios.TIOCOUTQ, one)
> + outq = struct.unpack("I", outq)[0]
> + if outq == 0:
> + break
> + time.sleep(0.01)
> + ksft_eq(outq, 0)
> +
> +
> +def tcp_sock_get_retrans(sock):
> + """Get the number of retransmissions for the TCP socket."""
> + info = sock.getsockopt(socket.SOL_TCP, socket.TCP_INFO, 512)
> + return struct.unpack("I", info[100:104])[0]
> +
> +
> +def run_one_stream(cfg, ipv4, remote_v4, remote_v6, should_lso):
> + cfg.require_cmd("socat", remote=True)
> +
> + port = rand_port()
> + listen_cmd = f"socat -{cfg.addr_ipver} -t 2 -u TCP-LISTEN:{port},reuseport /dev/null,ignoreeof"
> +
> + with bkg(listen_cmd, host=cfg.remote) as nc:
> + wait_port_listen(port, host=cfg.remote)
> +
> + if ipv4:
> + sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
> + sock.connect((remote_v4, port))
> + else:
> + sock = socket.socket(socket.AF_INET6, socket.SOCK_STREAM)
> + sock.connect((remote_v6, port))
> +
> + # Small send to make sure the connection is working.
> + sock.send("ping".encode())
> + sock_wait_drain(sock)
> +
> + # Send 4MB of data, record the LSO packet count.
> + qstat_old = cfg.netnl.qstats_get({"ifindex": cfg.ifindex}, dump=True)[0]
> + buf = b"0" * 1024 * 1024 * 4
> + sock.send(buf)
> + sock_wait_drain(sock)
> + qstat_new = cfg.netnl.qstats_get({"ifindex": cfg.ifindex}, dump=True)[0]
> +
> + # No math behind the 10 here, but try to catch cases where
> + # TCP falls back to non-LSO.
> + ksft_lt(tcp_sock_get_retrans(sock), 10)
> + sock.close()
> +
> + # Check that at least 90% of the data was sent as LSO packets.
> + # System noise may cause false negatives, it is what it is.
> + total_lso_wire = len(buf) * 0.90 // cfg.dev["mtu"]
> + total_lso_super = len(buf) * 0.90 // cfg.dev["tso_max_size"]
> + if should_lso:
> + if cfg.have_stat_super_count:
> + ksft_ge(qstat_new['tx-hw-gso-packets'] -
> + qstat_old['tx-hw-gso-packets'],
> + total_lso_super,
> + comment="Number of LSO super-packets with LSO enabled")
> + if cfg.have_stat_wire_count:
> + ksft_ge(qstat_new['tx-hw-gso-wire-packets'] -
> + qstat_old['tx-hw-gso-wire-packets'],
> + total_lso_wire,
> + comment="Number of LSO wire-packets with LSO enabled")
> + else:

[..]

> + if cfg.have_stat_super_count:
> + ksft_lt(qstat_new['tx-hw-gso-packets'] -
> + qstat_old['tx-hw-gso-packets'],
> + 100, comment="Number of LSO super-packets with LSO disabled")
> + if cfg.have_stat_wire_count:
> + ksft_lt(qstat_new['tx-hw-gso-wire-packets'] -
> + qstat_old['tx-hw-gso-wire-packets'],
> + 1000, comment="Number of LSO wire-packets with LSO disabled")

Why do you expect there to be some noise (100/1000) with the feature
disabled?