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 C8F683B27F3 for ; Sat, 25 Apr 2026 22:52:00 +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=1777157522; cv=none; b=D0dKCOfY8GWSYdFFaNltYs2elhVH9CQ6HgfxQzROvUF7tjJLHuCmmVAGgcxX3/uklPTb7QM5q8gooebNRxwW7P62foF012F9ObW14bohNZUf0niKX8XjCxTIvN3fhTo3/vo3LsQLYhK6qLNiZZ72RVyPvpaXC6NReEvmv9FPj8o= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777157522; 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=hpnzK/zgu/A6Zv7DPwwCAtkw5httzIJFFU5LtEVvMXWjmiDsGa8iqaaDPYqmpvhw1G8NpF2Dx/ZG/Uzp8m5Jkn8SsytDh+aS3qT9pqKLR6bMPoN6ujng2tPT8EGKrB5DIjouUu5FzJUmR13+6kQoMAvNA3Q1awRXa61hEgDyBJ0= 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=WAuqNxSG; 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="WAuqNxSG" Received: by mail-dy1-f202.google.com with SMTP id 5a478bee46e88-2ddd8ef5343so8847287eec.1 for ; Sat, 25 Apr 2026 15:52:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1777157520; x=1777762320; 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=WAuqNxSGVtbUCjNTKJOJdafRLxr4736F0MwgyrhkkZclXFKvxVn3msLMMKqeTNhJ+V ZAgVl8637QU0lnm9zO0TxVQZecAuw/eqqUqvfqiSr9aHaJ5brZoMo+DMRpZ91Q6o3NcF BPEwjdpQtz7XYqV72Fl26ogcnl6Lnl4TYYk/smyYMIdUXl4Z213Xg+oRvSYne6WA4Rby D5mfKDeSDrGTQTMaiu3i6UKeb/ECWk5QXK3uY8OUqPNtltV9kTLhSsw9wR7wdne0asjf 8BiUTkB3rZePspnQCeJFiDnVObAGWw7O2b5aD81tacLCN8tl9oSKnhYYclySknjtW6K6 RJRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1777157520; x=1777762320; 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=Hn5xnB1aprowmDxKewd4XEry8ECE4mbgfc759AYJ5P1Z+o65rvcEJG4BReLJ2nxyyZ vYkWT5z/+IOUNiOZJ1628pKR2/uRUJMhDhTH8wr6qJWu0MehuzCsSNqDKzchnwv7rGc4 GEKExZ9TEtcbbfA0G0pnxznh8sVU1JtOMh4Hvt7EOBScWk1+xF1qZyoMs/IEjCdkir5l KzGdcYTsOQPGgaZjoq8QbNxpiY1AnYkdw5uRvPScatv/AWBIV3GgaBAyGjzYv8pswEB+ XhoXbS/DrQfUNqcpplbelg/eQzBjdk2rkYMsF5iIbd8F/6N2X7ucGNC1/Pn9K2JqDhZH d2FQ== X-Forwarded-Encrypted: i=1; AFNElJ/NkCt6iOmAFdXQufaxjhGgjmxfgBY4mcDWDjAEQb8w+dzRCdQjIJNesaJnK95p4Gwu3sB/eG/oD5ItNW0=@vger.kernel.org X-Gm-Message-State: AOJu0YwTJyAuLntVKzPaCmyMe9AlOXKJriY42XlAfdUWkojH06bFe5N4 OOGs+ly+SXwIOilnjx+e2BeEl19E69BzzVnfWisvrCuguVM0BThHfIvqXAlFrHC1KyI7Skg1oAl TZWxY6NzCCg== 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:a05:7022:90a:b0:127:33e0:ea40 with SMTP id a92af1059eb24-12c73f7fbaamr18492849c88.15.1777157519599; Sat, 25 Apr 2026 15:51:59 -0700 (PDT) Date: Sat, 25 Apr 2026 15:49:43 -0700 In-Reply-To: <20260425224951.174663-1-irogers@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260425174858.3922152-1-irogers@google.com> <20260425224951.174663-1-irogers@google.com> X-Mailer: git-send-email 2.54.0.545.g6539524ca2-goog Message-ID: <20260425224951.174663-52-irogers@google.com> Subject: [PATCH v7 51/59] 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