From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f69.google.com (mail-pj1-f69.google.com [209.85.216.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 858B537A858 for ; Mon, 21 Sep 2026 05:08:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.69 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789967298; cv=none; b=B6gH1QGVVji3Q9IjC5ol/EHFAhQxEnvdMAN/BX+x40/SgtWJAKE5gfmWWjK5FUbe4ltrO4J9h6c0tlkIg9HZrqHArFNVhQ5kQ5AlgtSyg2ztDj2Ejb9P4oOZXZPrBfv3k07bciUasOMJofNIzO3D9lsM2GHSJbJyyOJNULYeoyw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789967298; c=relaxed/simple; bh=8Bk1bWXRTEwDqS7ftQKTbckk62xuO8EolOOidt6VleQ=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=sAhpuHveAUBm9PA/GHv26k+eQQBAPfrp77qufPrnBPX0csBwOJ8OMjvI1Pls11ccrgnB0z400ogINi+JpS0TvAwuLSFEzALIB5RHUiaEyWMICzKElIk8l429BrHH2OgrsZ04r2GUvMnq3mIMl6lXmy5sIUK73RInIdtK6w5yREE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=YnUSkE9s; arc=none smtp.client-ip=209.85.216.69 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--irogers.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="YnUSkE9s" Received: by mail-pj1-f69.google.com with SMTP id 98e67ed59e1d1-39e18af9f48so3998828a91.1 for ; Sun, 20 Sep 2026 22:08:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1789967296; x=1790572096; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=aJp30NLDE6VMNo04VO3UNO5Lbt1RIBaIrW7mzsnW58Q=; b=YnUSkE9sWFTYVJGZZ5FPzJbXGklL5EJu4e/NvWCyKvZTh6Y0bHb6Fp7sBX64uA3//d En5Kq5dIRipxHePRwwuJxX7fyAol4v6JXSfXEw/AfLwnKBH2Ab5YT5RBBsbjZM0cQJUO jcz4zAL+a7/MJLxw2FILyAaw7fVqoq+MjguaVzXKHGqoUXQk8tsW8RGDIDSTSD4qbbOT tJSWtgw3UG5K3V2hRqCiJyHNXN56Zkz0Y6VyWOCrG/lYjBWLx3zcoH6P+uwGnsZPY17o JpoIHpU9O1AyL8ViSyHlU5ZQ+pkKd7Fm2CMMi0yP1thNGSlLOw24YQdrEUOM5rsWSUjP 25eg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789967296; x=1790572096; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=aJp30NLDE6VMNo04VO3UNO5Lbt1RIBaIrW7mzsnW58Q=; b=G3164f77T4rQeazA8nzO7KEeh82jIUkyP7mEjuAY8bjXO4BQnJL5ID3kiRP9XQ7ldd /uouiYgiJKWXrrE9aeJJgIMHOXQR1WlENfB58fcX/uiA+OA9x6ZC/DdIof5vU0PUXuQy Fj3qT/UKX2rBNWv8c5rkepEuXJWyJmMZHd6Ieyyub5DNes70sy4fmAb2bXTT4R77CNWu SdDVr19BpbJASbI1d3wmvW8hVToQFtzvPIehRooVaJ6rk1Ozzl31IH5PWhjAkkglIuPS b2eWFtM/nMljWuLaQhVuDMeeSoI9GeOGMcWPK0rhWebcUUMppw5PAXxQAgcpzVjHLfNC CdIg== X-Forwarded-Encrypted: i=1; AKwUvBwSQqThB+849NqS/owpCzcpO2pkVYcW+yCd6+DyrOzFGTcSYkUlRnq1ziyLrjEVw6v0BQtubq4Wmh/bsuM=@vger.kernel.org X-Gm-Message-State: AFuF++lrXf0qC/SWOFiP0MV7/56ki0myvTsbbcGIA3VA6UFCOD7QhN21 zp3RbZ60RwNj5ScF3e5eO/SwcOUxSRfBUrC4DP9Cg4Q0K8o+8N5H+WsIKULWNzytSW6URJZh91w dIolXIh+qrA== X-Received: from dldz19-n1.prod.google.com ([2002:a05:701b:4193:10b0:143:9704:de05]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a17:90b:1ccc:b0:39e:3bcd:9130 with SMTP id 98e67ed59e1d1-39e3bcd9601mr16445457a91.20.1789967295633; Sun, 20 Sep 2026 22:08:15 -0700 (PDT) Date: Sun, 20 Sep 2026 22:06:48 -0700 In-Reply-To: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: X-Mailer: git-send-email 2.55.0.1082.g2b9226bbc0-goog Message-ID: Subject: [PATCH v2 30/49] perf python: Port futex-contention to perf module From: Ian Rogers To: irogers@google.com, acme@kernel.org, alice.mei.rogers@gmail.com, linux-perf-users@vger.kernel.org, namhyung@kernel.org Cc: adrian.hunter@intel.com, dapeng1.mi@linux.intel.com, james.clark@linaro.org, leo.yan@linux.dev, linux-kernel@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, tmricht@linux.ibm.com Content-Type: text/plain; charset="UTF-8" Port tools/perf/scripts/python/futex-contention.py to a standalone script in tools/perf/python/ using the perf module. Avoiding the embedded interpreter overhead improves execution speed by ~3.2x: ``` $ perf record -e syscalls:sys_*_futex -a sleep 1 ... $ time perf script tools/perf/scripts/python/futex-contention.py ... real 0m1.007s user 0m0.935s sys 0m0.072s $ time python3 tools/perf/python/futex-contention.py ... real 0m0.314s user 0m0.259s sys 0m0.056s ``` Additional improvements compared to the legacy script: - Consolidate per-(tid, uaddr) contention count, total_time, min_time, and max_time into a single LockStats class instead of maintaining three separate dictionaries. - Validate that uaddr and op tracepoint attributes are present on syscalls:sys_enter_futex samples rather than silently attributing missing fields to uaddr=0, op=0 (FUTEX_WAIT). - Add -i/--input CLI option support via argparse and full type annotations. Add a shell test (test_futex_contention_python.sh) to verify the standalone script. Assisted-by: Antigravity:gemini-3.1-pro Signed-off-by: Ian Rogers --- tools/perf/python/futex-contention.py | 93 +++++++++++++++++++ .../shell/test_futex_contention_python.sh | 67 +++++++++++++ 2 files changed, 160 insertions(+) create mode 100755 tools/perf/python/futex-contention.py create mode 100755 tools/perf/tests/shell/test_futex_contention_python.sh diff --git a/tools/perf/python/futex-contention.py b/tools/perf/python/futex-contention.py new file mode 100755 index 000000000000..d5bb8ca19699 --- /dev/null +++ b/tools/perf/python/futex-contention.py @@ -0,0 +1,93 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0 +"""Measures futex contention.""" +from __future__ import annotations + +import argparse +from collections import defaultdict +from typing import Dict, Tuple +import perf + +class LockStats: + """Aggregate lock contention information.""" + def __init__(self) -> None: + self.count = 0 + self.total_time = 0 + self.min_time = 0 + self.max_time = 0 + + def add(self, duration: int) -> None: + """Add a new duration measurement.""" + self.count += 1 + self.total_time += duration + if self.count == 1: + self.min_time = duration + self.max_time = duration + else: + self.min_time = min(self.min_time, duration) + self.max_time = max(self.max_time, duration) + + def avg(self) -> float: + """Return average duration.""" + return self.total_time / self.count if self.count > 0 else 0.0 + +process_names: Dict[int, str] = {} +start_times: Dict[int, Tuple[int, int]] = {} +session = None +durations: Dict[Tuple[int, int], LockStats] = defaultdict(LockStats) + +FUTEX_WAIT = 0 +FUTEX_PRIVATE_FLAG = 128 +FUTEX_CLOCK_REALTIME = 256 +FUTEX_CMD_MASK = ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME) + + +def handle_start(tid: int, uaddr: int, op: int, start_time: int) -> None: + """Handle a futex sys_enter event.""" + if (op & FUTEX_CMD_MASK) != FUTEX_WAIT: + return + try: + if session: + process = session.find_thread(tid) + if process: + process_names[tid] = process.comm() or "unknown" + except (TypeError, AttributeError): + pass + if tid not in process_names: + process_names[tid] = "unknown" + + start_times[tid] = (uaddr, start_time) + +def handle_end(tid: int, end_time: int) -> None: + """Handle a futex sys_exit event.""" + if tid not in start_times: + return + (uaddr, start_time) = start_times[tid] + del start_times[tid] + durations[(tid, uaddr)].add(end_time - start_time) + +def process_event(sample: perf.sample_event) -> None: + """Process a single sample event.""" + event_name = str(sample.evsel) + if event_name.startswith("evsel(syscalls:sys_enter_futex)"): + uaddr = getattr(sample, "uaddr", None) + op = getattr(sample, "op", None) + if uaddr is None or op is None: + return # Tracepoint fields missing, skip silent attribution to 0 + handle_start(sample.sample_tid, uaddr, op, sample.sample_time) + elif event_name.startswith("evsel(syscalls:sys_exit_futex)"): + handle_end(sample.sample_tid, sample.sample_time) + + +if __name__ == "__main__": + ap = argparse.ArgumentParser(description="Measure futex contention") + ap.add_argument("-i", "--input", default="perf.data", help="Input file name") + args = ap.parse_args() + + session = perf.session(perf.data(args.input), sample=process_event) + session.process_events() + + for ((t, u), stats) in sorted(durations.items()): + avg_ns = stats.avg() + print(f"{process_names.get(t, 'unknown')}[{t}] lock {u:x} contended {stats.count} times, " + f"{avg_ns:.0f} avg ns [max: {stats.max_time} ns, min {stats.min_time} ns]") diff --git a/tools/perf/tests/shell/test_futex_contention_python.sh b/tools/perf/tests/shell/test_futex_contention_python.sh new file mode 100755 index 000000000000..b7d6976e4f57 --- /dev/null +++ b/tools/perf/tests/shell/test_futex_contention_python.sh @@ -0,0 +1,67 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# futex-contention python test + +set -e + +shelldir=$(dirname "$0") +# shellcheck source=lib/setup_python.sh +. "${shelldir}"/lib/setup_python.sh + +# If we don't have the perf python module, we can't test +if ! "$PYTHON" -c 'import perf' > /dev/null 2>&1; then + echo "Skipping test, perf python module not found" + exit 2 +fi + +script_dir="$(dirname "$0")/../../python" +script_path="${script_dir}/futex-contention.py" + +if ! perf check feature -q libtraceevent > /dev/null 2>&1; then + echo "Skipping test, libtraceevent is disabled" + exit 2 +fi + + +if [ ! -f "$script_path" ]; then + echo "Skipping test, futex-contention.py not found at $script_path" + exit 2 +fi + +err=0 +temp_data="" + +cleanup() { + rm -f "${temp_data}" +} + +trap 'cleanup' EXIT TERM INT + +temp_data=$(mktemp /tmp/perf.data.XXXXXX) + +test_file_mode() { + echo "Testing futex-contention.py..." + # Some systems might not have syscalls:sys_enter_futex + if ! perf list | grep -q syscalls:sys_enter_futex; then + echo "Skipping test, syscalls:sys_enter_futex not found" + exit 2 + fi + + # Generate some futex events + if ! perf record -e syscalls:sys_enter_futex,syscalls:sys_exit_futex -a -o "${temp_data}" \ + -- sleep 0.5 2>/dev/null; then + echo "Skipping (record failed)" + exit 2 + fi + + if ! "$PYTHON" "$script_path" -i "${temp_data}" >/dev/null; then + echo "File mode test failed." + err=1 + else + echo "File mode test passed." + fi +} + +test_file_mode + +exit $err -- 2.55.0.1082.g2b9226bbc0-goog