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 11A9D4A0EE8 for ; Wed, 16 Sep 2026 12:06:45 +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=1789560413; cv=none; b=JbYhIIFFjjMED7zqvG2vLHfUb9P7u/VFwwEfcxUWSBa4P7FerAMm6Q8JIYC4eILImrpuBw6yE7UlPywg/H/LTTtRO3vyR+llGU66yzExoy1iRU2bvPFFVa91g8ArEjMsuR/0v7aU81Iiddo5zX/YWvhBvw41o/lxkwSgeJlqKE8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789560413; c=relaxed/simple; bh=PLUizAahm26SYUPuUUrJU3jhe2MbMJAs5y7MCSJ4EX4=; h=From:Subject:To:Cc:In-Reply-To:References:Content-Type:Date: Message-Id; b=C7x7CfglwE3dYVTHSWCv/C7ZasN4KfKSUtvaZT7/IYaxXnqPIrps6e6Ux/JBmdJe/bAX8NitIY5hHXdCmdsBe8Vyu2fHpxTpRGRsxofUtGlyT3yKh5Bb3wlH4MQYJhyRJAUUNxfwZdPkpzMBr+Ihn8suD0V0iPejXKaN7DnxCAM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NW+wrZyM; 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="NW+wrZyM" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 73C3C1F00898; Wed, 16 Sep 2026 12:06:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789560400; bh=yQzI2pOkVaa31kbqZIac7MtD9uP72RSvg1XJd+rdZpY=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=NW+wrZyMgvHWMYk6f+SAlMyMWSWb0pdVgRen5jX7o/2YvEunNU/TLYDSq35Ml78ju kpyVPDKRbn3ZImlo7nz/ajncy9PPT0MVk1lw62CjnNi6PSway8IPa3UxWII8kvo0hs 4WsStVJWL2Xf5uW7i/nRgwN/lELtufwlgoujkjdocAfH6tOwEcEmUzvhPLgn7nUUWa xpMs0vYJCAQlQ+bAFAbITjJGq781i9kuvYondQ2Q5hahzd4mPLWFtpSibBn2LRr1Mo p4kFsnYZJNTHGPdyLBQyAgAegXfdpZaMAyyu4qWoXV8P+zCrVirMpOxELGrCP211Wu 9M2qxhmmF9HYQ== 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: <20260916114740.48230-12-acme@kernel.org> References: <20260916114740.48230-1-acme@kernel.org> <20260916114740.48230-12-acme@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Wed, 16 Sep 2026 12:06:40 +0000 Message-Id: <20260916120640.73C3C1F00898@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/20260916114740.4823= 0-1-acme@kernel.org?part=3D11