From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dl1-f74.google.com (mail-dl1-f74.google.com [74.125.82.74]) (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 C58AF369999 for ; Thu, 23 Apr 2026 19:44:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776973477; cv=none; b=GIsO39qSqlp7IvNWxf9lIZFSgcQHDm4Q11WroVSvS95IedX92Dac+UTUe1eOj5XNmAVcz/l3KwY500U8oN76MNoSLFA4FHJpWQJIqcmTwlYDT5E1vYZfmjZPqFuZDWX5AIoyOofV4aznh+EU4rCywwYfS7e4GtruvJUiOV4F+I0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776973477; c=relaxed/simple; bh=OYv4zaUPaqpE4bB6sOH2vYIPz0Hv5QaIWWSyHOE1dvo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=iC/nWgVPDCtkici85zLV5X724adLNYBV/r/YEj2h88iFpITu688tt0rKKBidJTwApfjRqXhVfMwVFer3MSzd/y5S00G5V52eBIFt0V5WNWcc66r9yeGn85/i7iY2D74MwNnXCaaAcz8nnoAQhP9qux26wvqB1o3la3Fp8jAK1Dw= 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=iU2IwgW3; arc=none smtp.client-ip=74.125.82.74 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="iU2IwgW3" Received: by mail-dl1-f74.google.com with SMTP id a92af1059eb24-12db37213daso9328139c88.1 for ; Thu, 23 Apr 2026 12:44:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1776973474; x=1777578274; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=dcIdOgL+7uarIK1UbnVrTv+/pxGdH2WlwKMAxRVHpls=; b=iU2IwgW3sj2v+x5zW3zPvbhemcBevGiIK+8girRxhLpeOWD+Rd/Z+o8MQLt/kpH9Ee SUXbkSTH8K5dzMgpMMVxn9fGpN1x9qovWYcZmZ85sPG4JVv9nZ4r8dJrhoYAHaAAKZ5V JUHAD5oOISrGzNP2HElLu1u5a5ig7ccT7ITcSco0AUUrEFVdsmq5dES1COL12VVEc+XG j1rxfy5JQTQISRnWC1BmjijvRhImvm5+Ccy0Csbmhb4bs8XEnLurTwD0IO6OFrx9D9PW KkmFMYsUg0/IjdhqOFkmN97ki8GrpGyvf8GqnUNRrW5he6lmmXiByQL+tecWlzd96wm7 3D9A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1776973474; x=1777578274; h=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; bh=dcIdOgL+7uarIK1UbnVrTv+/pxGdH2WlwKMAxRVHpls=; b=JXIVoszx8R9HuaZ+9y4G6u7B3jOZQi5OWl8GsLw2V1QfKKUe3ZJxIJnQNygcVgBUyz iW9VH9OVDkkIs2S+3EAfo9pyDlTijQ6/WDX/L8jWruBTNSWur9SYKC6Tr0gJhw8w4NEv WHQ684Epw68JRzbmEh+MF2XEIWicqZjtcjYHXQ3uQAhL3FE7rfsBwyQx4008OoLQgbr2 Lt3P5w/x48qfMBJr6+Lz3KC04aJxYHLvSZjQJhca1nV/9gIcDCwvtVQ1evzxoq1uTxol tAI2ckoSRLbYZXVoGfLD1ltY3VsrNKEZ+AqLkmRiDaHbBYRCAkdaojUyHEkrgN+DDPWn GQMQ== X-Forwarded-Encrypted: i=1; AFNElJ+S/pOk+ztpMmGU051smUwjXsMRCOHvapzVWbfCcbO3wg4T5pFypa1RvhD3FXIqHJeeigk2vWUVEHYAtfMR5jiM@vger.kernel.org X-Gm-Message-State: AOJu0YxF+9vCBy0YieoEfvk8GCK7mv5h+hT1gaQcD0/n9LG8Y4uXFucA Y+8UlZKYRbaNxeUwb08+W/cj/RADgwEosWtgiSNULhSs+9RnWARRVPPJv0Z6UNmCE6GtD79IOkT wZ8DhkQpsIQ== X-Received: from dly15-n1.prod.google.com ([2002:a05:701b:204f:10b0:12a:83c5:a16f]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7022:69a:b0:128:d967:466c with SMTP id a92af1059eb24-12c73f9f65fmr15041977c88.24.1776973473698; Thu, 23 Apr 2026 12:44:33 -0700 (PDT) Date: Thu, 23 Apr 2026 12:43:58 -0700 In-Reply-To: <20260423194428.1846255-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260423161006.1762700-1-irogers@google.com> <20260423194428.1846255-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260423194428.1846255-2-irogers@google.com> Subject: [PATCH v4 29/58] perf futex-contention: Port futex-contention to use python module From: Ian Rogers To: acme@kernel.org, adrian.hunter@intel.com, james.clark@linaro.org, leo.yan@linux.dev, namhyung@kernel.org, tmricht@linux.ibm.com Cc: alice.mei.rogers@gmail.com, dapeng1.mi@linux.intel.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, Ian Rogers Content-Type: text/plain; charset="UTF-8" Rewrite tools/perf/scripts/python/futex-contention.py to use the python module and various style changes. By avoiding the overheads in the `perf script` execution the performance improves by more than 3.2x as shown in the following (with PYTHON_PATH and PERF_EXEC_PATH set as necessary): ``` $ perf record -e syscalls:sys_*_futex -a sleep 1 ... $ time perf script tools/perf/scripts/python/futex-contention.py Install the python-audit package to get syscall names. For example: # apt-get install python3-audit (Ubuntu) # yum install python3-audit (Fedora) etc. Press control+C to stop and show the summary aaa/4[2435653] lock 7f76b380c878 contended 1 times, 1099 avg ns [max: 1099 ns, min 1099 ns] ... 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 ``` Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers --- v2: 1. Fixed Module Import Failure: Corrected the type annotations from [int, int] to Tuple[int, int] . The previous code would raise a TypeError at module import time because lists cannot be used as types in dictionary annotations. 2. Prevented Out-Of-Memory Crashes: Replaced the approach of storing every single duration in a list with a LockStats class that maintains running aggregates (count, total time, min, max). This ensures O(1) memory usage per lock/thread pair rather than unbounded memory growth. 3. Support for Custom Input Files: Added a -i / --input command-line argument to support processing arbitrarily named trace files, removing the hardcoded "perf.data" restriction. 4. Robust Process Lookup: Added a check to ensure session is initialized before calling session. process() , preventing potential NoneType attribute errors if events are processed during initialization. --- tools/perf/python/futex-contention.py | 87 +++++++++++++++++++++++++++ 1 file changed, 87 insertions(+) create mode 100755 tools/perf/python/futex-contention.py diff --git a/tools/perf/python/futex-contention.py b/tools/perf/python/futex-contention.py new file mode 100755 index 000000000000..7c5c3d0ca60a --- /dev/null +++ b/tools/perf/python/futex-contention.py @@ -0,0 +1,87 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0 +"""Measures futex contention.""" + +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_WAKE = 1 +FUTEX_PRIVATE_FLAG = 128 +FUTEX_CLOCK_REALTIME = 256 +FUTEX_CMD_MASK = ~(FUTEX_PRIVATE_FLAG | FUTEX_CLOCK_REALTIME) + + +def process_event(sample: perf.sample_event) -> None: + """Process a single sample event.""" + def handle_start(tid: int, uaddr: int, op: int, start_time: int) -> None: + if (op & FUTEX_CMD_MASK) != FUTEX_WAIT: + return + if tid not in process_names: + try: + if session: + process = session.process(tid) + if process: + process_names[tid] = process.comm() + except (TypeError, AttributeError): + return + start_times[tid] = (uaddr, start_time) + + def handle_end(tid: int, end_time: int) -> None: + 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) + + event_name = str(sample.evsel) + if event_name == "evsel(syscalls:sys_enter_futex)": + uaddr = getattr(sample, "uaddr", 0) + op = getattr(sample, "op", 0) + handle_start(sample.sample_tid, uaddr, op, sample.sample_time) + elif event_name == "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]") -- 2.54.0.rc2.533.g4f5dca5207-goog