From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-dy1-f201.google.com (mail-dy1-f201.google.com [74.125.82.201]) (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 999323F0755 for ; Fri, 24 Apr 2026 16:49:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.82.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777049375; cv=none; b=nieLn+Umf5bi2IWQ/SHuQpVndryNdBneGlm+9m1xc0PJLoe/1iOlDvnfZia+5Fg/qJk99koql7fV1gWRR6a6SQI3x/Mg3UMCRlmvXg24NedWwKpT6GMJKAMkeDuRInRJsN5By3UO8hSaef62yjWLf58jHtV6IuWZjsYSIf9xams= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777049375; c=relaxed/simple; bh=jeR4Y5tYrqM+VRciyZ38jmj8C+EvBF6bkN0wvPo/M1Y=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=QHb/8ptb/UhC+KfZBYT84GI8YovHd7g2Zhhi5lhvprBUrn1ltBE5BLeOOB09ctBKsnwX/Y86OemMiJHIEKjvCrnceaE85VXeX5OnnEAQgj5ALgHnaABV/3awbl1ejsKA2TWPK1/Rv0I4nhUZOG28I7ls7kwwyNxCOOQ0phKA7+s= 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=blzUn35+; arc=none smtp.client-ip=74.125.82.201 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="blzUn35+" Received: by mail-dy1-f201.google.com with SMTP id 5a478bee46e88-2bdf75bc88fso10403927eec.0 for ; Fri, 24 Apr 2026 09:49:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777049373; x=1777654173; 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=4vO51mkUv8czx4QMNQNbvlHwQFmUDbpKAVfeUaPjKEk=; b=blzUn35+c8OBxK/98/wCqtww7g1jm4zB7aMsvDbcCzdaNn7Q0OlcIftDlUbw9eyQjN un1djRqhbbWI+GTHEQgNxWNxLWtLK+8OKPiMSxlRenQgWTFqVFE9a7MCx9FHI2RUmLj2 Pz2V0TS7hUjvfxZkeWuOyNFI0KHGN9AbSs/rCjMk4BuMtkC41Lpd51ouCK8l8Csni7bV BTLBzBhP7ECblUOzUq+Too3+oPZJyydOvvJc9Xs6orVTQDiD/kZUdwwnTDTgygx7GI6D hrT/BQUJqwCHICWglPgJjTqwCqeNRKpuYLLtMtfYYhwlskOz8ZB8Cc+q4+Od2JLDJ7rY RmBA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777049373; x=1777654173; 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=4vO51mkUv8czx4QMNQNbvlHwQFmUDbpKAVfeUaPjKEk=; b=dNiz1OXRtDYbKFx8YeNLkF++cgF1Tp9RWxuQC/3VgWT30bqr1IV40GVHUXvapKTusY WY41qhw2F+y9AbUHNMF+kUprlw7dzXzck8DjSMF15gaJWIIIXF0VHVbMGxz1UecW4YBW tmOJb0cPRk8B9mEo+XTcnLatJxx4jS+5TL8tMoX/EWvFftWhu+GV4/YSApy8N1XeJOwD qez6Oi5aat5lgGrE0rY+2zUPfkcH5DApHQhYxgThM3c5fr5BtddG7gg+/Vvj+iTNBW1T VNiLJP9Orn75qBU7HrqvUzpbMBSmC2+qnrHogEn4n/s9G6oE1n9xT3FiLcL1/qn6ZPhH vGmg== X-Forwarded-Encrypted: i=1; AFNElJ9GmtosVnvwNy4LQKU2qfZ66k1yMCbCgqK6O+E4WslRT3d2fxqKryU1MxTzpsXa4LSfkFeP9dm05SDeArtBz0nz@vger.kernel.org X-Gm-Message-State: AOJu0Yw5LnWQ1xI1C7gooE/B/pVB1liU0gV2x+TGcUaL5tU+r/T3dKom cJmivUgxooxvb6ypMWKCr8nBztwmw560v241J0/dxgCYb8H+ZlUuQd1AZlpVuAStc4Lv6fmYned 3N8tLQ1OUmw== X-Received: from dycoy3.prod.google.com ([2002:a05:7301:fc03:b0:2e0:fe68:96c7]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:7300:5ba1:b0:2dd:8ac2:9f7a with SMTP id 5a478bee46e88-2eada6d6539mr2779618eec.11.1777049372661; Fri, 24 Apr 2026 09:49:32 -0700 (PDT) Date: Fri, 24 Apr 2026 09:47:13 -0700 In-Reply-To: <20260424164721.2229025-1-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: <20260423163406.1779809-1-irogers@google.com> <20260424164721.2229025-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260424164721.2229025-52-irogers@google.com> Subject: [PATCH v5 51/58] perf wakeup-latency: Port wakeup-latency 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" Port the legacy Perl script wakeup-latency.pl to a python script using the perf module in tools/perf/python. The new script uses a class-based architecture and leverages the perf.session API for event processing. It measures wakeup latency by tracking timestamps of sched:sched_wakeup and sched:sched_switch events. Complications: - Used min() and max() built-in functions instead of if blocks to satisfy pylint recommendations. - pylint warns about the module name not being snake_case, but it is kept for consistency with the original script name. Assisted-by: Gemini:gemini-3.1-pro-preview Signed-off-by: Ian Rogers --- v2: - Fixed Wakeup Latency Logic: Modified the script to track wakeup timestamps per task (using sample.pid as the key) instead of per CPU. This ensures that context switches are correctly paired with the specific task that was woken up, even if multiple tasks are woken up on the same CPU or if a task is migrated to a different CPU before running. - Prevented Memory Growth: Added del self.last_wakeup[next_pid] after successful latency calculation to prevent the dictionary from growing unbounded over time. - Added Error Tracking: Added try-except blocks around tracepoint field access in process_event() and tracked missing fields in self. unhandled instead of ignoring them. --- tools/perf/python/wakeup-latency.py | 88 +++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100755 tools/perf/python/wakeup-latency.py diff --git a/tools/perf/python/wakeup-latency.py b/tools/perf/python/wakeup-latency.py new file mode 100755 index 000000000000..1b0db115abcf --- /dev/null +++ b/tools/perf/python/wakeup-latency.py @@ -0,0 +1,88 @@ +#!/usr/bin/env python3 +# SPDX-License-Identifier: GPL-2.0-only +"""Display avg/min/max wakeup latency.""" + +import argparse +from collections import defaultdict +import sys +from typing import Optional, Dict +import perf + +class WakeupLatency: + """Tracks and displays wakeup latency statistics.""" + def __init__(self) -> None: + self.last_wakeup: Dict[int, int] = defaultdict(int) + self.max_wakeup_latency = 0 + self.min_wakeup_latency = 1000000000 + self.total_wakeup_latency = 0 + self.total_wakeups = 0 + self.unhandled: Dict[str, int] = defaultdict(int) + self.session: Optional[perf.session] = None + + def process_event(self, sample: perf.sample_event) -> None: + """Process events.""" + event_name = str(sample.evsel) + sample_time = sample.sample_time + + if "sched:sched_wakeup" in event_name: + try: + pid = sample.pid + self.last_wakeup[pid] = sample_time + except AttributeError: + self.unhandled[event_name] += 1 + elif "sched:sched_switch" in event_name: + try: + next_pid = sample.next_pid + wakeup_ts = self.last_wakeup.get(next_pid, 0) + if wakeup_ts: + latency = sample_time - wakeup_ts + self.max_wakeup_latency = max(self.max_wakeup_latency, latency) + self.min_wakeup_latency = min(self.min_wakeup_latency, latency) + self.total_wakeup_latency += latency + self.total_wakeups += 1 + del self.last_wakeup[next_pid] + except AttributeError: + self.unhandled[event_name] += 1 + else: + self.unhandled[event_name] += 1 + + def print_totals(self) -> None: + """Print summary statistics.""" + print("wakeup_latency stats:\n") + print(f"total_wakeups: {self.total_wakeups}") + if self.total_wakeups: + avg = self.total_wakeup_latency // self.total_wakeups + print(f"avg_wakeup_latency (ns): {avg}") + else: + print("avg_wakeup_latency (ns): N/A") + print(f"min_wakeup_latency (ns): {self.min_wakeup_latency}") + print(f"max_wakeup_latency (ns): {self.max_wakeup_latency}") + + if self.unhandled: + print("\nunhandled events:\n") + print(f"{'event':<40s} {'count':>10s}") + print(f"{'-'*40} {'-'*10}") + for event_name, count in self.unhandled.items(): + print(f"{event_name:<40s} {count:10d}") + + def run(self, input_file: str) -> None: + """Run the session.""" + self.session = perf.session(perf.data(input_file), sample=self.process_event) + self.session.process_events() + self.print_totals() + +def main() -> None: + """Main function.""" + parser = argparse.ArgumentParser(description="Trace wakeup latency") + parser.add_argument("-i", "--input", default="perf.data", help="Input file") + args = parser.parse_args() + + analyzer = WakeupLatency() + try: + analyzer.run(args.input) + except IOError as e: + print(e, file=sys.stderr) + sys.exit(1) + +if __name__ == "__main__": + main() -- 2.54.0.545.g6539524ca2-goog