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 5A9024D9F9F for ; Wed, 16 Sep 2026 18:45:24 +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=1789584340; cv=none; b=fBEQ9/73ihvO/qW/CabR7s8Fs8aYpBMdhYvq3F6LXPQZRPER7J8eSSZlQoHLUFq2HdNILdziSE+UbxEx3HpHVewyPkTgcrcPOtVq5NfxMEi2xUWU7h6M9RC6olfRMKSaZHLVpfdLZe84xK3OyPpLUsFXv13tW5KTxO1oRJGiyNA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789584340; c=relaxed/simple; bh=S3nZ6dB2jzT8phWYrICSqOdFxbOuiEf2H0ZH//CCDvQ=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=V48ZtnZRlIHsiSfzLooXPEWD+n5L7yoD4efskSr/pQHjPGNK4aqJAvMVRco9BZWnRUlaiTPRa1E1Vg5D0oVJdCPgtjdzydU97A0QEAx/hvm+JxevuBcsNYKfuiHwL/LDANb546zLe18Da9WE+whNmINqLePV8GBihrDGNlD8Fyc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=I8RNGKhp; 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="I8RNGKhp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 93AA31F0089A; Wed, 16 Sep 2026 18:45:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789584320; bh=4lmU05ImbZTzn9m98EtFqa27aJBeblxKhaYcWzVNTuM=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=I8RNGKhpjZ/NuQ/PM6348F0B2i+UR7F8wyuOLgBGPefn1cHq6mhE+rQJZM4mRk+2N FrlyGSkHoiwsssuKBzvhhEwGbNxIyliKK0FyaFHJ1iHRZNy4RV3ze9ecjp0Bj6OfuX QO33+w+/Z1Y6CanwTT6P87Q1yaZIydoDOmBJ6orNy9ZtbdCRJBuzdFoDzXDAZoWU9l DISoZKDNh6ktL4xCoipYSPujlrbNcRqdLGRTryiYetVpiMLjnxhI2nD1wDESixfCZT qaibcD01r91bjHzQMv2BYS/IaKNxCztU5QR3ZbAEQGwn1Bg/c27i1DI/kWCmrHem2+ r2UP9JpjNtuDQ== From: sashiko-bot@kernel.org Subject: Re: [PATCH 11/12] perf mem record: Request PERF_SAMPLE_CPU by default Reply-To: sashiko-reviews@lists.linux.dev To: "Arnaldo Carvalho de Melo" Cc: linux-perf-users@vger.kernel.org In-Reply-To: <20260916183215.54305-12-acme@kernel.org> References: <20260916183215.54305-1-acme@kernel.org> <20260916183215.54305-12-acme@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 16 Sep 2026 18:45:20 +0000 Message-Id: <20260916184520.93AA31F0089A@smtp.kernel.org> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: > From: Arnaldo Carvalho de Melo >=20 > The data-type profiling per-sample stream keys cross-CPU contention on > sample->cpu: without PERF_SAMPLE_CPU the cpu field is the (u32)-1 "no > CPU info" sentinel, documented as such in perf_session__deliver_event(), > and same-instance reads and writes from different cores are > indistinguishable from same-CPU traffic, so pahole's false-sharing > detector cannot tell them apart. >=20 > builtin-record.c already defines --sample-cpu and 'perf mem record' > forwards unknown options to the record parser, so passing it explicitly > works today; make it the default, next to the -d (addr) and -W (weight) > the command already requests, documenting it in perf-mem(1). >=20 > The rec_argv array is sized as nine arguments per memory PMU plus the > user arguments, not counting the arguments __cmd_record() adds itself, > up to eight with all the optional flags. On PMUs with separate load and > store events the four event arguments plus the fixed ones already filled > the array to its last slot, so this new argument would write past it; > reserve space for the fixed arguments explicitly. >=20 > Assisted-by: LLM > Signed-off-by: Arnaldo Carvalho de Melo Sashiko has reviewed this patch and found no issues. It looks great! --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20260916183215.5430= 5-1-acme@kernel.org?part=3D11