From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f202.google.com (mail-dy1-f202.google.com [74.125.82.202]) (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 E14CF37C911 for ; Sat, 25 Apr 2026 17:49:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777139402; cv=none; b=hW040pd/Qzlqfmfih1CYMaF6rWkCnU2212tmT4OCQbGI25Tk67VGpQvdCkuBReXVBex0QfBgJG4BRrede7wmQ0ju00VlRicbIT8XnQmtW4RE4E2tiaEojN4wxy80gv8PLxbPxEtYGxt14VXaZOTfaAdhN6y2VbckNFC5FgOsQCs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777139402; c=relaxed/simple; bh=FRJkB1Cquz79cOSRZrWQZxDQ+1Gx96tDBQLRgM6VsPA=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=qWuwnozWaSpHYRWsSP7Fi/XKEihYf7hILdvz6JKRRhXFTxDO5vesIF+i9isfg8P9UG1VjsC+wcb036NXdSuT5oJqEivHeesGHeoI6inDujXwHZ5xJE4sXWA2bRfOrQ22MOmMHy3zb4E4+eiWl/7JWOM1ZjeyO38T57UpzZ3SoLs= 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=d899G5D3; arc=none smtp.client-ip=74.125.82.202 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="d899G5D3" Received: by mail-dy1-f202.google.com with SMTP id 5a478bee46e88-2de07c12745so24740325eec.1 for ; Sat, 25 Apr 2026 10:49:59 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777139399; x=1777744199; 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=GkS04/94NBW5ShfL0EcvB/IZEgEtB93nGkm6zSZzY+Q=; b=d899G5D3jgaZkoO1V+9j1uORyrPIk357QxlUmw58hJUfmFd4hmi8FQazOpWB6S25YJ DUltgiRXyjH+jbTmorgaj9MqeSuq0fWGlqpayNRKDnmD61Y1lz2PSE2l2+RxcwIFodaq NsmHoQv6oIJDJiCx5Nj0W+9ZcOzxs5j+sVUWPvWd0i0FVyryZvH1q27oPDSz8KH0aIIV KkzjzUHci6KxXtOThHDYqnCIGgRLO4f/UGTnJbl5yzxKK1/Q3IJHjfziQSpx15yxIDCi ozuKSeMPrnAmoOcC94Xp9piLvTzMs7bf3PiA86VcqpiPrDxIUWSdKEN2kYPqjUHt3k5z l/tA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777139399; x=1777744199; 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=GkS04/94NBW5ShfL0EcvB/IZEgEtB93nGkm6zSZzY+Q=; b=bPiYEqJ2CDOgiZq1bWCUYN0HEY5+cMmVbpLWqJHv5X7XZ1Vm26FZdHMoZAHU8R97xT cn2yx+Qw6mVBxbG3+lQoBlzqbhbDsJ6AXjYy23MwImM5mgBlL2l7Tj1LHJS4I09/THX4 i2Y7bnX7F9M9atcXUAhIfY568XSOoPiCNwEFuo98Ndo2giZaMhRk2vdrY+iW0Rutfc1T nwEuMGzOu/vDXNxQiglpLk1tLHA0uuteq2iPBA2lm/nK7yl1a99AZD1/QAasLUIND/OF t4a9ABzXV0o/QFkMw7OkJ34xPBvCljGRt7HEKqEpTFL7c/ou75rhQRZpUdYncJJpI2MQ c6Sg== X-Forwarded-Encrypted: i=1; AFNElJ/634wIDha6OmK769Qo5XuKSjOClGEIFEAPDu5VnpJ4ch8dOORGON3PaS6wNS6Yyce3+1Wqxz+f8SmvBU7UikSx@vger.kernel.org X-Gm-Message-State: AOJu0Yx115jhdbhJ4/i+YifpHWnrH5TxpDb/ElGDvjEtC0zdrwyRSChf 7zD6QDJJ06BdjubWyNxiUZ0NkT12HjGfUjlcPUFH27CLOwGY4B24SpGimtsx6RLcCIXlt5elLdP 5jFg0cEljpA== X-Received: from dybsc19.prod.google.com ([2002:a05:7301:4b13:b0:2e6:a17a:3fa3]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7300:7491:b0:2df:7b88:a1b0 with SMTP id 5a478bee46e88-2e4873f31a7mr22475971eec.27.1777139398906; Sat, 25 Apr 2026 10:49:58 -0700 (PDT) Date: Sat, 25 Apr 2026 10:48:27 -0700 In-Reply-To: <20260425174858.3922152-1-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: <20260424164721.2229025-1-irogers@google.com> <20260425174858.3922152-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260425174858.3922152-30-irogers@google.com> Subject: [PATCH v6 29/59] 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..1fc87ec0e6e5 --- /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.find_thread(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]") -- 2.54.0.545.g6539524ca2-goog