From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 6E656542817; Tue, 22 Sep 2026 12:27:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790080054; cv=none; b=qDerVPuPl6FrY4M3bjxayHYp1mXNxHbUzJodMg//4CWpXyFnEl+dnI1Mp/qqdIhLmYcFxq1saDVQhXAiTvEC5SDFuXBiXe45GTqFv+wpXJCevOw7kQXjkj1p9CnzFX6Bk90dWrfiUR0aEPaftfxeNEHKg9Fx5MIdr2dKJ/mhgwI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790080054; c=relaxed/simple; bh=wxs2XxPjV4TsQRFaOZYnOMvLj8n/AHgTau/C8WqoWYA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=O1l/KlA3xjzunAnd11Mo2tYu8NtfM2VEU2S2/yQ/hGV/T4RqFgzI1pVRCva1HcUyw3sc28UmShZZGv0l2B0CJIFHuTJWZN2AsgNGAdK9Ewudk+2QcN1RX8Lw8HvOqbiD9K7POjh5BVRs405Gyp8wmq448reNs3S3F09RlfByXVA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kn2T4Erw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kn2T4Erw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E52311F00898; Tue, 22 Sep 2026 12:27:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1790080051; bh=eLkJrvnAeHJo+bmYbI04lAs1t48D/OuOuWuJv/uf5x0=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=kn2T4ErwBh5d1UvDyjn+p95G47Es66PmknKm0QSSIvAIPN5sZlGGe01A1KS/sUfqa eK40cEiNzfqvwSXFNSMYjSO0NJThPiG4+sZPaEWngWQ3RbdEnJwKmHZXhBQGl9rHXh fN/Fr4CDMvsSC4rZkABYCWNhQ1Cr9uJMT/t/cuAlA/INzZ3eZ/hwRF1w6ldXoH3SXA bi6Y2YlMJVpUoKK4p3hI7cvZboVhOujismS31QvSiA8eWBwMlpPMAYk8GdXwZFA6CU wr3NJPIrqx/GdbxA8ibplVaTvgGizMb/RXFO26f76ZNTJzorQZ4l6gHOw5FrR416F5 6J7kNz1Ays2mA== From: Arnaldo Carvalho de Melo To: Namhyung Kim Cc: Ingo Molnar , Thomas Gleixner , James Clark , Jiri Olsa , Ian Rogers , Adrian Hunter , Clark Williams , linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, Arnaldo Carvalho de Melo Subject: [PATCH v3 6/7] perf mem record: Request PERF_SAMPLE_CPU by default Date: Tue, 22 Sep 2026 14:26:22 +0200 Message-ID: <20260922122623.1029132-7-acme@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260922122623.1029132-1-acme@kernel.org> References: <20260922122623.1029132-1-acme@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Arnaldo Carvalho de Melo The data type profiling per-sample stream keys cross-CPU contention on sample->cpu; without PERF_SAMPLE_CPU that field is the (u32)-1 "no CPU info" sentinel, so same-instance accesses from different cores are indistinguishable from same-CPU traffic. 'perf mem record' already passes -d (addr) and -W (weight) explicitly to the record parser, add --sample-cpu as well and document it in perf-mem(1). The rec_argv array only had room for nine arguments per PMU plus the user arguments, not counting the up to eight __cmd_record() adds itself, which a new argument would overflow on PMUs with separate load and store events; reserve space for the fixed arguments too. Assisted-by: LLM Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/Documentation/perf-mem.txt | 4 ++++ tools/perf/builtin-mem.c | 11 +++++++++-- 2 files changed, 13 insertions(+), 2 deletions(-) diff --git a/tools/perf/Documentation/perf-mem.txt b/tools/perf/Documentation/perf-mem.txt index 4d164836d0943119..fe51c5e3333dc4a0 100644 --- a/tools/perf/Documentation/perf-mem.txt +++ b/tools/perf/Documentation/perf-mem.txt @@ -14,6 +14,10 @@ DESCRIPTION ----------- "perf mem record" runs a command and gathers memory operation data from it, into perf.data. Perf record options are accepted and are passed through. +It also requests the address (-d), the weight (-W, where supported) and the +CPU id (--sample-cpu) of every sampled access by default; the CPU id is what +lets per-sample analysis tell reads and writes to the same data from +different cores apart from same-CPU traffic. "perf mem report" displays the result. It invokes perf report with the right set of options to display a memory access profile. By default, loads diff --git a/tools/perf/builtin-mem.c b/tools/perf/builtin-mem.c index 6101a26b3a781e69..f25592bc52728655 100644 --- a/tools/perf/builtin-mem.c +++ b/tools/perf/builtin-mem.c @@ -99,8 +99,8 @@ static int __cmd_record(int argc, const char **argv, struct perf_mem *mem, argc = parse_options(argc, argv, options, record_usage, PARSE_OPT_KEEP_UNKNOWN); - /* Max number of arguments multiplied by number of PMUs that can support them. */ - rec_argc = argc + 9 * (perf_pmu__mem_events_num_mem_pmus(pmu) + 1); + /* Max number of arguments per PMU plus the fixed ones added below. */ + rec_argc = argc + 8 + 9 * (perf_pmu__mem_events_num_mem_pmus(pmu) + 1); if (mem->cpu_list) rec_argc += 2; @@ -135,6 +135,13 @@ static int __cmd_record(int argc, const char **argv, struct perf_mem *mem, rec_argv[i++] = "-d"; + /* + * The data type profiling per-sample stream keys cross-CPU contention + * on sample->cpu; without PERF_SAMPLE_CPU it is the (u32)-1 'no CPU + * info' sentinel. + */ + rec_argv[i++] = "--sample-cpu"; + if (mem->phys_addr) rec_argv[i++] = "--phys-data"; -- 2.55.0