More robust error handling if fio fails

README.md

@@ -4,6 +4,11 @@ A robust, CrystalDiskMark‑style storage benchmark for Linux, built on [`fio`](
 
 It runs the same four tests CrystalDiskMark does, plus a dedicated **SLOG / sync‑write latency profile** for diagnosing ZFS ZIL performance (NFS / iSCSI / VM sync workloads). It auto‑detects the best IO engine and whether `O_DIRECT` works on the target, and falls back to a basic `dd` test when `fio` isn't installed.
 
+## Quick Install
+```bash
+wget https://git.mreschke.net/mreschke/speedtest-hd/raw/branch/master/speedtest-hd.py && chmod a+x speedtest-hd.py
+```
+
 ---
 
 ## Table of contents

speedtest-hd.py

@@ -32,6 +32,7 @@ import glob
 import json
 import os
 import shutil
+import socket
 import statistics
 import subprocess
 import sys
@@ -179,6 +180,19 @@ def step(message: str) -> None:
     log(f"  {ERR.paint('▶', BOLD, CYAN)} {ERR.paint(message, DIM)}")
 
 
+# Messages already shown by warn(); fio tends to fail the same way on every run,
+# so we de-duplicate to avoid printing the identical error 8 times.
+_warned: set[str] = set()
+
+
+def warn(message: str) -> None:
+    """A de-duplicated warning line -> stderr (shown even without --verbose)."""
+    if message in _warned:
+        return
+    _warned.add(message)
+    log(f"  {ERR.paint('!', BOLD, YELLOW)} {ERR.paint(message, YELLOW)}")
+
+
 def vsection(title: str) -> None:
     """A clear, ruled header for one --verbose fio section -> stderr."""
     width = 78
@@ -367,10 +381,41 @@ def run_fio(
         return _aggregate(data["jobs"], _direction_of(rw))
     except (json.JSONDecodeError, KeyError, ValueError):
         # fio failed or produced no parseable JSON; report zeros rather than
-        # crashing the whole run (verbose mode above shows what went wrong).
+        # crashing the whole run, but surface *why* so an all-zero table isn't
+        # silent. fio writes its real error to stderr (engine not loadable,
+        # permission denied, io_uring disabled, etc.).
+        detail = proc.stderr.strip() or proc.stdout.strip() or "(no output)"
+        first = detail.splitlines()[0] if detail else "(no output)"
+        warn(f"fio failed (exit {proc.returncode}): {first}")
         return FioResult.zero()
 
 
+def fio_health() -> tuple[bool, str]:
+    """Check that fio can actually *run* on this host before we rely on it.
+
+    Some packaged/Homebrew fio builds are compiled for a newer CPU baseline
+    (e.g. x86-64-v3 / AVX2) than the machine has, so fio dies with SIGILL
+    ("illegal hardware instruction") the instant it starts -- which would
+    otherwise show up as a silent table of zeros. ``fio --version`` exercises
+    that same startup path without needing sudo or touching the disk.
+
+    Returns ``(ok, detail)``; ``detail`` is fio's version on success or a short
+    failure description (a negative return code means killed by signal N).
+    """
+    try:
+        proc = subprocess.run(["fio", "--version"], capture_output=True, text=True)
+    except OSError as exc:                       # e.g. ENOEXEC on a bad binary
+        return False, str(exc)
+    if proc.returncode == 0:
+        return True, proc.stdout.strip() or "ok"
+    if proc.returncode < 0:                       # killed by a signal
+        sig = -proc.returncode
+        names = {4: "SIGILL (illegal instruction)", 6: "SIGABRT", 11: "SIGSEGV"}
+        return False, f"crashed: {names.get(sig, f'signal {sig}')}"
+    detail = (proc.stderr.strip() or proc.stdout.strip() or "").splitlines()
+    return False, f"exit {proc.returncode}" + (f": {detail[0]}" if detail else "")
+
+
 def fio_probe(path: str, engine: str, direct: bool) -> bool:
     """Throwaway 1s fio job to see if an (engine, O_DIRECT) combo works here.
 
@@ -442,6 +487,8 @@ def banner(title: str, cfg: Config, extra: Sequence[str] = ()) -> None:
         + OUT.paint("│", BOLD, CYAN)
     )
     print(OUT.paint("╰" + "─" * inner + "╯", BOLD, CYAN))
+    print(_meta_line(f"Host    : {OUT.paint(socket.gethostname(), CYAN)}"))
+    print(_meta_line(f"Date    : {OUT.paint(time.strftime('%Y-%m-%d %H:%M:%S %Z'), CYAN)}"))
     print(_meta_line(f"Target  : {OUT.paint(cfg.path, CYAN)}"))
     for line_ in extra:
         print(_meta_line(line_))
@@ -694,18 +741,43 @@ def main(argv: Optional[Sequence[str]] = None) -> int:
         benchfile=os.path.join(path, "speedtest-hd.bench"),
     )
 
-    have_fio = shutil.which("fio") is not None
+    fio_path = shutil.which("fio")
+    have_fio = fio_path is not None
+
+    # fio may be installed yet non-functional (e.g. a build compiled for AVX2 on
+    # a CPU without it dies with SIGILL). Verify it actually runs, so we fall back
+    # or error clearly instead of emitting a silent table of zeros.
+    fio_broken = ""
+    if have_fio:
+        ok, detail = fio_health()
+        if not ok:
+            have_fio = False
+            fio_broken = detail
+            warn(f"fio is installed ({fio_path}) but {detail}.")
+            warn("This is usually an fio build compiled for a newer CPU than this")
+            warn("host (often a Homebrew/AVX2 binary on an older Atom/Celeron). Check")
+            warn("'which fio'; prefer your distro's package (dnf/apt install fio).")
 
     # Resolve the mode: explicit flag wins; otherwise fio if available, else dd.
     mode = cfg.mode
     if mode in ("cdm", "slog") and not have_fio:
+        if fio_broken:
             print(ERR.paint("ERROR:", BOLD, RED)
-              + " --fio/--slog require fio (apt install fio / pacman -S fio).",
+                  + f" --fio/--slog need a working fio, but fio {fio_broken} on this"
+                  + " host. Reinstall fio, or use --dd for the dependency-free test.",
+                  file=sys.stderr)
+        else:
+            print(ERR.paint("ERROR:", BOLD, RED)
+                  + " --fio/--slog require fio (dnf install fio / apt install fio).",
                   file=sys.stderr)
         return 1
     if mode is None:
         if have_fio:
             mode = "cdm"
+        else:
+            if fio_broken:
+                print(OUT.paint(f"\nfio is installed but {fio_broken} -- falling back "
+                                "to the basic dd test.", YELLOW))
             else:
                 print(OUT.paint("\nfio is not installed -- falling back to basic dd test.",
                                 YELLOW))