[RFC net-next v2 3/5] selftests: drv-net: add an iperf performance test

[Stanislav Fomichev <sdf.kernel@gmail.com>]

Add the drivers/net/hw/performance target. Report throughput and
retransmits from Iperf3Runner when requested.

Single-stream iperf3 throughput is flaky and can change considerably
between back-to-back runs on the same hosts.

Tested on two mlx5 hosts. Captured metric output:

  # # ktap-metric-policy-json: {"display_label":"Gbps","name":"throughput","regression":{"better":"higher","compare":"p50","relative_tolerance":0.05},"summarize":"p50"}
  # # ktap-metric-policy-json: {"name":"tcp.retransmits","summarize":"max"}
  # # ktap-metric-json: {"host":"local","name":"throughput","time":10.685632,"type":"scalar","value":48.561920255183196}
  # # ktap-metric-json: {"host":"remote","name":"tcp.retransmits","time":10.68565,"type":"scalar","value":0}

Signed-off-by: Stanislav Fomichev <sdf@fomichev.me>
---
 tools/testing/selftests/Makefile              |  2 +-
 .../drivers/net/hw/performance/Makefile       | 10 +++++++
 .../drivers/net/hw/performance/config         |  1 +
 .../drivers/net/hw/performance/iperf.py       | 27 +++++++++++++++++++
 .../drivers/net/hw/performance/settings       |  1 +
 .../selftests/drivers/net/lib/py/load.py      | 24 +++++++++++++++--
 6 files changed, 62 insertions(+), 3 deletions(-)
 create mode 100644 tools/testing/selftests/drivers/net/hw/performance/Makefile
 create mode 100644 tools/testing/selftests/drivers/net/hw/performance/config
 create mode 100755 tools/testing/selftests/drivers/net/hw/performance/iperf.py
 create mode 100644 tools/testing/selftests/drivers/net/hw/performance/settings

diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index 273853937c25..7523f378e026 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -152,7 +152,7 @@ TARGETS_HOTPLUG = cpu-hotplug
 TARGETS_HOTPLUG += memory-hotplug
 
 # Networking tests want the net/lib target, include it automatically
-ifneq ($(filter net drivers/net drivers/net/hw,$(TARGETS)),)
+ifneq ($(filter net drivers/net drivers/net/hw drivers/net/hw/performance,$(TARGETS)),)
 ifeq ($(filter net/lib,$(TARGETS)),)
 	INSTALL_DEP_TARGETS := net/lib
 endif
diff --git a/tools/testing/selftests/drivers/net/hw/performance/Makefile b/tools/testing/selftests/drivers/net/hw/performance/Makefile
new file mode 100644
index 000000000000..5d53ef548306
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/hw/performance/Makefile
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0
+
+TEST_PROGS := iperf.py
+
+TEST_INCLUDES := \
+	$(wildcard ../lib/py/*.py ../../lib/py/*.py) \
+	$(wildcard ../../../../net/lib/py/*.py) \
+	#
+
+include ../../../../lib.mk
diff --git a/tools/testing/selftests/drivers/net/hw/performance/config b/tools/testing/selftests/drivers/net/hw/performance/config
new file mode 100644
index 000000000000..6450f34933e6
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/hw/performance/config
@@ -0,0 +1 @@
+CONFIG_IPV6=y
diff --git a/tools/testing/selftests/drivers/net/hw/performance/iperf.py b/tools/testing/selftests/drivers/net/hw/performance/iperf.py
new file mode 100755
index 000000000000..415fb67f4100
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/hw/performance/iperf.py
@@ -0,0 +1,27 @@
+#!/usr/bin/env python3
+# SPDX-License-Identifier: GPL-2.0
+
+"""Measure TCP throughput with iperf3."""
+
+from os import path
+import sys
+
+sys.path.insert(0, path.join(path.dirname(path.abspath(__file__)), ".."))
+
+from lib.py import Iperf3Runner, NetDrvEpEnv, ksft_exit, ksft_run
+
+
+def tcp(cfg):
+    """Measure TCP throughput."""
+    Iperf3Runner(cfg).measure_bandwidth(report=True)
+
+
+def main():
+    """Run the iperf performance test."""
+    with NetDrvEpEnv(__file__, nsim_test=False) as cfg:
+        ksft_run([tcp], args=(cfg,))
+    ksft_exit()
+
+
+if __name__ == "__main__":
+    main()
diff --git a/tools/testing/selftests/drivers/net/hw/performance/settings b/tools/testing/selftests/drivers/net/hw/performance/settings
new file mode 100644
index 000000000000..e7b9417537fb
--- /dev/null
+++ b/tools/testing/selftests/drivers/net/hw/performance/settings
@@ -0,0 +1 @@
+timeout=0
diff --git a/tools/testing/selftests/drivers/net/lib/py/load.py b/tools/testing/selftests/drivers/net/lib/py/load.py
index e24660e5c27f..a7da025b4e21 100644
--- a/tools/testing/selftests/drivers/net/lib/py/load.py
+++ b/tools/testing/selftests/drivers/net/lib/py/load.py
@@ -4,7 +4,8 @@ import re
 import time
 import json
 
-from lib.py import ksft_pr, cmd, ip, rand_port, wait_port_listen
+from lib.py import cmd, ip, ksft_metric, ksft_metric_policy, ksft_pr, \
+    rand_port, wait_port_listen
 
 
 class Iperf3Runner:
@@ -53,12 +54,20 @@ from lib.py import ksft_pr, cmd, ip, rand_port, wait_port_listen
             kwargs["timeout"] = duration + 5
         return cmd(cmdline, **kwargs)
 
-    def measure_bandwidth(self, reverse=False):
+    def measure_bandwidth(self, reverse=False, report=False):
         """
         Runs an iperf3 measurement and returns the average bandwidth (Gbps).
         Discards the first and last few reporting intervals and uses only the
         middle part of the run where throughput is typically stable.
         """
+        if report:
+            ksft_metric_policy(
+                "throughput", summarize="p50",
+                regression={"compare": "p50", "better": "higher",
+                            "relative_tolerance": 0.05},
+                display_label="Gbps")
+            ksft_metric_policy("tcp.retransmits", summarize="max")
+
         self.start_server()
         result = self.start_client(duration=10, reverse=reverse)
 
@@ -77,6 +86,17 @@ from lib.py import ksft_pr, cmd, ip, rand_port, wait_port_listen
         stable = samples[3:-3]
 
         avg = sum(stable) / len(stable)
+        retransmits = out.get("end", {}).get("sum_sent", {}).get(
+            "retransmits")
+        if report:
+            if not isinstance(retransmits, int) or \
+                    isinstance(retransmits, bool):
+                raise ValueError("iperf3 did not report TCP retransmits")
+            receiver = "remote" if reverse else "local"
+            sender = "local" if reverse else "remote"
+            ksft_metric("throughput", avg, kind="scalar", host=receiver)
+            ksft_metric("tcp.retransmits", retransmits, kind="scalar",
+                        host=sender)
 
         return avg
 
-- 
2.53.0-Meta