From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f197.google.com (mail-pl1-f197.google.com [209.85.214.197]) (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 53E6F3EC687 for ; Wed, 16 Sep 2026 06:53:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.197 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789541583; cv=none; b=YEmaQjbsFLdDTBqQGcltaDKiZXE3SaZrdV/05QnnPJK8Y0hZdcXKQzBkCgCegWnZHCpAlpkbKSh35kj7ieqyOzHLtVgi0VE16U0oXv+/8L/F2GGOzU1m81woEfI+mN/vDljKUvKlWuQj0OZ8435FRbeYkCd2ZOUK/9ZinKMO4zs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789541583; c=relaxed/simple; bh=nVrDjAaLjz/G0gXgjT4ygxlgmvIatuz8zfzY1CnsCg4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=kY34nsboUFPiOPnJ1MOti64AdADdSGHzFHr4G2wrktUDbORw4oY7HYlX4y3jI4QN7IM62EhYJ5zVxjFJ+jjD2HYITXF9Jaq+7R8GJwW5PbC41vUx5N0roPlchxJOPwDuora/pQSOvvKd0+N+cGUwCIIDB0ncCE3PRzV1LVkMcu8= 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=WqHqDMxe; arc=none smtp.client-ip=209.85.214.197 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="WqHqDMxe" Received: by mail-pl1-f197.google.com with SMTP id d9443c01a7336-2dd8920c132so15364585ad.0 for ; Tue, 15 Sep 2026 23:53:02 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1789541582; x=1790146382; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=gyb7wILWN2ttrIjNBf5YgT+03fCZnF3+pV/Z9u6pTzc=; b=WqHqDMxeHBxz1VsQFUCp1QSKeMRIB3ul4ZKaX5+l5/gzWJTlcuG/W9AkDyKOKShN/t JAXlJV6kx9XjtEeR5dGh+FkaOMgLtN9sRgUB1ibkLXrzk/96l3HnvVvODvml5dUrPTLs RoR2b4VIyLDZdffsAvHZ7MIb3GZspgNKgjdEvnfFDaVXGbXZc0TlX3KoJQNH9vhwNzIT 2fSwBdl7WUDMJqk/e95lMqZ4WFdr7F2cjxBdmc1qhZPQ1EBRYd/Z2GNK0YIom+oa6tLC XADtGePm+Zm7v+rdXuQR/A9ItisJ9mgqxMRmvMCgcOJz7m1SWU7xbqvoIIY9efmkyZTx AkDA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1789541582; x=1790146382; h=content-type: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:content-type; bh=gyb7wILWN2ttrIjNBf5YgT+03fCZnF3+pV/Z9u6pTzc=; b=I/UyuP4c8uWS1Qoq7bvsI8CBOXgSWgNMTPWm5kcfxasnRcam1Y5bBRYzT4QXBMR0p0 owXnBYqHtz6/FcKZ0+w8nhIBEMC8ogdHQe2H8rnOUESYErr6hI/HwxXnhI/aLYf4lqQX U9ELTl1W/ogIeAR7ie4BZUIGvgUgxrbyDCcE80CKm+rUYEeyoWyNNHlB76VvbWVDC0DC M8cXz8arwIfGEjG7RHGvl3kKOFbHGuMK1V5uHE28BeUt088XitU8iHZ1G31sgd16F6B9 CUrynrb5JODJzM0DJ/RxCV5SmRqNQinK5PFX2kM7sz6Y0fE9WOrrnIkV2Jv3+1AnLQ2a EbcA== X-Gm-Message-State: AFuF++k9v4HpWkRMRE7is6tmIeOtaOD5NUdW0P/1AFU5AukXQzfpdmO1 cbuCx3Lt7MZNvhmUYCyKth46U9OUptuyUcpLgw2k2sHIFvIDrDPKm/rb72LEzlGV3SeATKep7XN rVbjahUVPIg== X-Received: from dybtt4.prod.google.com ([2002:a05:7300:f404:b0:339:7bd3:e896]) (user=irogers job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:1990:b0:2d9:b60d:7755 with SMTP id d9443c01a7336-2dd8dbf0507mr30934165ad.1.1789541581583; Tue, 15 Sep 2026 23:53:01 -0700 (PDT) Date: Tue, 15 Sep 2026 23:52:43 -0700 In-Reply-To: <20260916065248.3153556-1-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: <20260916065248.3153556-1-irogers@google.com> X-Mailer: git-send-email 2.55.0.1032.g73a4cd73de-goog Message-ID: <20260916065248.3153556-5-irogers@google.com> Subject: [PATCH v2 4/9] perf Documentation: Add tip for hybrid event merging From: Ian Rogers To: irogers@google.com, acme@kernel.org, ak@kernel.org, ak@linux.intel.com, andi@firstfloor.org, namhyung@kernel.org Cc: linux-perf-users@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Add informative text outlining the IPC imbalances associated with merging cross-hybrid core events like cycles. Signed-off-by: Ian Rogers Assisted-by: Antigravity:gemini-3.1-pro --- tools/perf/Documentation/tips.txt | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/perf/Documentation/tips.txt b/tools/perf/Documentation/tips.txt index ebf12a8c5db5..1c7b309fe6e8 100644 --- a/tools/perf/Documentation/tips.txt +++ b/tools/perf/Documentation/tips.txt @@ -66,3 +66,4 @@ For latency profiling, try: perf record/report --latency For parallelism histogram, try: perf report --hierarchy --sort latency,parallelism,comm,symbol To analyze particular parallelism levels, try: perf report --latency --parallelism=32-64 To see how parallelism changes over time, try: perf report -F time,latency,parallelism --time-quantum=1s +When merging events like cycles, different core frequencies and instructions per cycle mean the counts may not fairly reflect time spent in a function. -- 2.55.0.1032.g73a4cd73de-goog