From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f202.google.com (mail-pg1-f202.google.com [209.85.215.202]) (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 E91BA4218B1 for ; Tue, 28 Apr 2026 07:21:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.202 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777360863; cv=none; b=DHW6LUC0u/ffH1D9Y0GIpPrD37sdQb2fIAJbi/oQ/8Z7ging9WHxPaQ/d28cVUWCm+sbfWTu46sG9V/s/7I5wWW6xhWSCWeMStILkhfNL3z06KGZoQHbciWnRZqYpl8ZUgSoxm/julPOlIMB/HNjBavjR0jhRukwIHLaRiC/R20= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777360863; 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=RoPNiHXn/5gQ284oZ96EnouPUytab1pBi6WBvE7OXTfGnkwufttBHI5R/Ce6WVOjaHdFigavPbS6CmBw+QVxOI6HlaImOFFeB31klDjuSF8XSkNCvqjM/WdG4mrp+BI4t1LyvMVzagz1QsLl7Y2oYvtz/e4bUpmlZERcrvbVh9s= 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=rzokUCui; arc=none smtp.client-ip=209.85.215.202 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="rzokUCui" Received: by mail-pg1-f202.google.com with SMTP id 41be03b00d2f7-c7985752be1so4374501a12.0 for ; Tue, 28 Apr 2026 00:21:01 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777360861; x=1777965661; 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=rzokUCuiqMJgbvkCpnXAYIlw55LZlCDtruVim2u2Ux0ipms0vmyAeIrFxNnVhN8bWL H1F+nmOzO0kjPtNMTI1A2wFca6/IL2XhRfucPe76BiKGOs96rLxr/4GpJktVF/wX0i6G QKyOmHAMqNpHQTYxTr30qxtdfnVYPFA9i48G9xX9X88k89PWqOP2FqDPJp0QuZDWDft2 71D8G03sadat261S9zmB9bhVdewNuYIRCiM6LIThp+MsPscanSFhlJwhG3mx927Essx6 NEBFXESklI3iRH9/dOdYzFFioigkbHRv3TAIwy1eW5ljPMyfjAwfvQyZ/bCfOKuRIj6a nBTw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777360861; x=1777965661; 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=kUmtbC6b9jI5Ah8eDsxMaPoo8i8++vLUkJ8nQxGU96F7vst4S91+MMbiDyE9ZXLbo9 tNsNG/KzH7c6A/KgQarHRnTi6eWjusXSO1e22iyVz/PK89ISQMCobwoKIfw8ojusDB2O E1+hvc4dehmTkhMRoYqpu5NbtHKEihbk48H4LWFM6xgsut4CEunt99VHThpOTPO0nEP9 JFCh4MHSVz5wkM3tEgVskz7GwaYcC0k4BHi2XSlJL31LjeHPC3RXvpwSiQyXD2md7NHN xnys803U3UFOn9aCPWd0gT8YGRST4D/t8sO+A7xUraHUTBKUPWwk852HGOn9P/aaZOQ4 jpmA== X-Forwarded-Encrypted: i=1; AFNElJ9EL0ogiOvCuVyF1CKYlPhb97bEEbAKKD0mP3eVO6peDe+hXg5Cmc/mJBR5puXOQ+P4rrXNBj1dME4ot9kmFea4@vger.kernel.org X-Gm-Message-State: AOJu0Yx5ExQ5yRXynxorpiDB0LUOCl21pJUvyCNRGj4xda3tEp1CKpCN 8Bl5mRBuZ+ff2P7vtODpQxOesv+OLIW4GvJq8WKz5ml8Bak+VcNbN+J5v3pkAGR3PgXzYqS4W7i vycdkwcu66A== X-Received: from pgac11.prod.google.com ([2002:a05:6a02:294b:b0:c76:a6b1:ed23]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a20:a120:b0:3a2:f14a:4290 with SMTP id adf61e73a8af0-3a39c27ff64mr2278598637.38.1777360860923; Tue, 28 Apr 2026 00:21:00 -0700 (PDT) Date: Tue, 28 Apr 2026 00:18:56 -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: <20260428071903.1886173-52-irogers@google.com> Subject: [PATCH v8 51/58] perf wakeup-latency: Port wakeup-latency 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" 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