[RFC net-next v2 4/5] selftests: drv-net: add a kperf runner

@@ -141,6 +141,14 @@ Arguments used to construct the communication channel.
   for netns - name of the "remote" namespace
   for ssh - name/address of the remote host
 
+kperf
+~~~~~
+
+Performance tests which use kperf expect ``kperf-client`` in ``PATH`` on the
+local host and ``kperf-server`` in ``PATH`` on both endpoints. Kperf is an
+optional dependency; tests which require it are skipped when it is not
+installed.
+
 Example
 =======
 

@@ -33,7 +33,8 @@ KSFT_DIR = (Path(__file__).parent / "../../../../..").resolve()
     from net.lib.py import ksft_eq, ksft_ge, ksft_in, ksft_is, ksft_lt, \
         ksft_ne, ksft_not_in, ksft_raises, ksft_true, ksft_gt, ksft_not_none
     from drivers.net.lib.py import set_ethtool_feat
-    from drivers.net.lib.py import GenerateTraffic, Remote, Iperf3Runner
+    from drivers.net.lib.py import GenerateTraffic, Remote, Iperf3Runner, \
+        KperfResult, KperfRunner
     from drivers.net.lib.py import NetDrvEnv, NetDrvEpEnv, NetDrvContEnv
 
     __all__ = ["NetNS", "NetNSEnter", "NetdevSimDev", "UserNetNS",

@@ -53,7 +54,8 @@ KSFT_DIR = (Path(__file__).parent / "../../../../..").resolve()
                "ksft_ne", "ksft_not_in", "ksft_raises", "ksft_true", "ksft_gt",
                "ksft_not_none", "ksft_not_none",
                "NetDrvEnv", "NetDrvEpEnv", "NetDrvContEnv", "GenerateTraffic",
-               "Remote", "Iperf3Runner", "set_ethtool_feat"]
+               "Remote", "Iperf3Runner", "KperfResult", "KperfRunner",
+               "set_ethtool_feat"]
 except ModuleNotFoundError as e:
     print("Failed importing `net` library from kernel sources")
     print(str(e))

@@ -52,11 +52,13 @@ KSFT_DIR = (Path(__file__).parent / "../../../..").resolve()
 
     from .env import NetDrvEnv, NetDrvEpEnv, NetDrvContEnv
     from .feat import set_ethtool_feat
+    from .kperf import KperfResult, KperfRunner
     from .load import GenerateTraffic, Iperf3Runner
     from .remote import Remote
 
     __all__ += ["NetDrvEnv", "NetDrvEpEnv", "NetDrvContEnv", "GenerateTraffic",
-                "Remote", "Iperf3Runner", "set_ethtool_feat"]
+                "Remote", "Iperf3Runner", "KperfResult", "KperfRunner",
+                "set_ethtool_feat"]
 except ModuleNotFoundError as e:
     print("Failed importing `net` library from kernel sources")
     print(str(e))

@@ -0,0 +1,161 @@
+# SPDX-License-Identifier: GPL-2.0
+
+"""Run and parse kperf network performance measurements."""
+
+import re
+import shlex
+import subprocess
+import uuid
+from dataclasses import dataclass
+
+from lib.py import cmd, ksft_metric, ksft_metric_policy, ksft_pr, \
+    rand_port, wait_port_listen
+
+
+_SECTION_RE = re.compile(r"==\s+(Source|Target)\b")
+_RATE_RE = re.compile(r"\b(Tx|Rx)\s*([0-9]+(?:\.[0-9]+)?)\s+Gbps\b")
+_TCP_HEADER = "TCP retrans reord rtt rttvar d_ce snd_wnd cwnd"
+_TCP_ROW_RE = re.compile(r"^\s*(?:[^:\s]+:\s*)?(\d+)(?:\s+\d+){6}\s*$")
+
+
+@dataclass
+class KperfResult:
+    """Aggregate throughput (Gbps) and retransmits of both endpoints."""
+
+    source_throughput: float
+    target_throughput: float
+    source_retransmits: int
+    target_retransmits: int
+
+
+class KperfRunner:
+    """Manage kperf servers and run measurements between test endpoints."""
+
+    def __init__(self, env):
+        self.env = env
+        self._pid_file = f"/tmp/ksft-kperf-{uuid.uuid4().hex[:8]}.pid"
+        self._port = rand_port()
+        self._started = []
+        env.require_cmd("kperf-client", local=True)
+        env.require_cmd("kperf-server", local=True, remote=True)
+
+    def _server(self, remote, kill=False):
+        host = self.env.remote if remote else None
+        address = self.env.remote_addr if remote else self.env.addr
+        args = ["kperf-server", "--pid-file", self._pid_file]
+        if kill:
+            args.append("--kill")
+        else:
+            args += ["--addr", address, "--port", str(self._port)]
+        return cmd(shlex.join(args) if remote else args, host=host,
+                   fail=not kill)
+
+    def __enter__(self):
+        try:
+            for remote in (False, True):
+                self._server(remote)
+                self._started.append(remote)
+            wait_port_listen(self._port)
+            wait_port_listen(self._port, host=self.env.remote)
+        except Exception:
+            self.close()
+            raise
+        return self
+
+    def close(self):
+        """Stop the started kperf servers."""
+        failures = []
+        while self._started:
+            command = self._server(self._started.pop(), kill=True)
+            if command.ret:
+                failures.append(command)
+        if failures:
+            details = "\n".join(str(command) for command in failures)
+            raise RuntimeError(f"failed to stop kperf server(s)\n{details}")
+
+    def __exit__(self, _exc_type, _exc_value, _exc_tb):
+        self.close()
+
+    def run(self, client_args=(), report=False):
+        """Run kperf and optionally report throughput and retransmits."""
+        argv = ["kperf-client", "--src", self.env.remote_addr,
+                "--dst", self.env.addr, "--src-svc", str(self._port),
+                "--dst-svc", str(self._port)]
+        argv += [str(arg) for arg in client_args]
+        command = cmd(argv, background=True)
+        try:
+            command.process(terminate=False, fail=False, timeout=300)
+        except subprocess.TimeoutExpired as error:
+            command.proc.kill()
+            command.process(terminate=False, fail=False)
+            raise RuntimeError(f"kperf client timed out\n{command!r}") \
+                from error
+        if command.ret:
+            raise RuntimeError(
+                f"kperf client exited with status {command.ret}\n{command!r}")
+
+        try:
+            result = self.parse(command.stdout + "\n" + command.stderr)
+        except ValueError:
+            ksft_pr(command)
+            raise
+
+        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")
+            for host, throughput, retransmits in (
+                    ("remote", result.source_throughput,
+                     result.source_retransmits),
+                    ("local", result.target_throughput,
+                     result.target_retransmits)):
+                ksft_metric("throughput", throughput, kind="scalar",
+                            host=host)
+                ksft_metric("tcp.retransmits", retransmits, kind="scalar",
+                            host=host)
+        return result
+
+    @staticmethod
+    def parse(output):
+        """Parse human-readable kperf client output."""
+        throughput = {"Source": [], "Target": []}
+        retransmits = {"Source": [], "Target": []}
+        section = None
+        in_tcp = False
+
+        for line in output.splitlines():
+            match = _SECTION_RE.search(line)
+            if match:
+                section = match.group(1)
+                in_tcp = False
+                continue
+            if section is None:
+                continue
+
+            match = _RATE_RE.search(line)
+            if match:
+                direction, value = match.groups()
+                if (section, direction) in (("Source", "Tx"),
+                                             ("Target", "Rx")):
+                    throughput[section].append(float(value))
+                continue
+
+            if _TCP_HEADER in line:
+                in_tcp = True
+                continue
+            if in_tcp:
+                match = _TCP_ROW_RE.match(line)
+                if match:
+                    retransmits[section].append(int(match.group(1)))
+
+        values = (*throughput.values(), *retransmits.values())
+        if not all(values):
+            raise ValueError("incomplete kperf result")
+
+        return KperfResult(sum(throughput["Source"]),
+                           sum(throughput["Target"]),
+                           sum(retransmits["Source"]),
+                           sum(retransmits["Target"]))