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 B67133D47A0 for ; Tue, 28 Apr 2026 07:20:17 +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=1777360819; cv=none; b=aI5ixQTKEiI3F0bGgbzibr3ZpZu/qDYHXEM/OfzOs0evdl/ezyHyVubcEQuXMkhehMIJP/jkNQnUUMGap5vCO1SuhYDGvPImoHwkj6Ig28M/dWYLb1Ujzw5zDDO580qJYrR4Ys/22NG6iilzIa2XlsQlgmaL6lMmhShftGiAibE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777360819; c=relaxed/simple; bh=u5c/am2jfjZWYiMa5qBJlKPhc8lQ2M2Vd/M2zXOpRq0=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=lWdrhiLqS19qJosfFWVgvqYb0eSBBwDsrQZXhXjz3U7ONTHenDC18/TZqUF9AxlN3hu7ozpMvW3vR8W/wDXSFNgA6q60gqFfWHfICoGv1cgNZ3CAuqy2advsjmB5D3w/dti0pFEzizGdzo9rKcqvjMEmldY7Wcc4ziMcDuPo1uc= 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=vwR2zJQt; 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="vwR2zJQt" Received: by mail-dy1-f202.google.com with SMTP id 5a478bee46e88-2e60238adb1so27753191eec.0 for ; Tue, 28 Apr 2026 00:20:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777360817; x=1777965617; 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=hkP+7Ld+msio4991lavZB6N3kEKOAmCVypgwmqxtk64=; b=vwR2zJQteGe7pgPojtR+Jl8WPP50g9WKbp/vdy0VqKc+h1NoZCJUkNZ/ncleW2a5dM /Hqe7yaVgNQfZDIigBP/sAuRNBtp1TmvbyzRVBbvUIbLw46fQoq7cX+LpW8OUzqn/bT8 B4g6OpV2GrQobzi9uMOLmyoE0mwql5sx8bjEKTSZvI/LhhUHB3ri1LykjzcByHOvNCfd 43P6TEWt/v4l/N0LggnVwvWnrmjiDj02kSK649WHw8PQ2h3a4aABZ2lCVdBorlcmvBm0 +Iy1zYM7AwVlyCfPJfHgls1K5aDd21i7NUg7yedkvd5aPbcuRFdbyJzbRZZJB3gBoiiw 7ZAA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777360817; x=1777965617; 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=hkP+7Ld+msio4991lavZB6N3kEKOAmCVypgwmqxtk64=; b=F0u2yntKfiOluVrUcIlG7CbiEpmUFKW9IiL6KTMIDFSVBW285+ePBxpen00pJlFRLq SyJRf9GOtMM1UgY/lPOIIEBsyL0TUSZv/ccO4DlMQ5gRtVG7q7GGnz5du9/B5J//tnL3 B6cqKeTgDzBTPYtnRc6b9EfsVQMBaeNQ9Wx4ozCbPCc2JQcZWcCvXVuquEzfGSqtmSI8 l0OhCO4axl2t10oN3UvdyvFHKz2b2aksE5w9RgUhtv0FJoV3T6HN0iWLHIM0AwvZ+wxG K//umUpEjN7PsZLHGRi6tciEZkh4v3bDHd5iIExqIKpds8QLQUYJ9Ew6czUZaRUuHmVV n6hg== X-Forwarded-Encrypted: i=1; AFNElJ8ellDhYeu/IH3xRBu/pJ5fkZAJxBs3qzh/zVbVDweeVrw4w/gt6hIh+2AO4iGNYt/y3t8BGTRSpaZY4tT+GAei@vger.kernel.org X-Gm-Message-State: AOJu0Yzd5SLnVZsCybwNiKcOZfvZ3O8B9AN2KCH53L1ZZYNc/9VP7lxw cbRsQbr6YfT3jH+kQNkYtjE3/uT66ZrrShZ31h/zsbX3G6GrgK1rrcCsqGCEoHetPMbjI/wzm1R tRxYRADRl3Q== X-Received: from dycol2.prod.google.com ([2002:a05:7301:db82:b0:2dd:8e19:2d13]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7300:bb07:b0:2db:2089:460f with SMTP id 5a478bee46e88-2ed0a0cc6ccmr948754eec.19.1777360816818; Tue, 28 Apr 2026 00:20:16 -0700 (PDT) Date: Tue, 28 Apr 2026 00:18:34 -0700 In-Reply-To: <20260428071903.1886173-1-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: <20260425224951.174663-1-irogers@google.com> <20260428071903.1886173-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260428071903.1886173-30-irogers@google.com> Subject: [PATCH v8 29/58] perf futex-contention: Port futex-contention to use python module From: Ian Rogers To: acme@kernel.org, namhyung@kernel.org Cc: adrian.hunter@intel.com, alice.mei.rogers@gmail.com, dapeng1.mi@linux.intel.com, james.clark@linaro.org, leo.yan@linux.dev, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, mingo@redhat.com, peterz@infradead.org, tmricht@linux.ibm.com, 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. v8: - Fixed process name resolution in handle_start to fall back to 'unknown' instead of early return to prevent data loss. --- 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..021dd3c2aa2f --- /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): + process_names[tid] = "unknown" + 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