From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 72F9ACA0EC4 for ; Tue, 12 Aug 2025 20:46:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=QOg1TD8bTIja1jsfCfz0y6W3vB735g3sOL05FkDgwYo=; b=fw2EFp80vzoI87cDhsT5fM7aJ4 ZDZEabSOqjFXbIk+cMjE/YP9b64WYf1SB0aDHAL4R5y4lpjRJ/3tWPkuu7givAT6xqggyZ/4c/5LV nkLvB5/9A3Ul8CWX5VGDRoCHeBvI3M2o8Bra0Z/ibGWSvy0FtybUM1p5sPe78frL7fkm/6gfzj8Ni jtAmBme2pyvZedEkZCaoBmnB3yv4zrLhdWW36Iqbxx3ZnADT53raq2zi6e47R7XyuCYBpPkK44ayv HMqtLiO8Sn+bqin4CFVgMYz5oX9mWlq3QlEpvqsgqZnS7AavVxkZvdR2EJ08qdJc+mWksPE0Z3g5B zuIome7Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1ulvsi-0000000Bzw4-0HDB; Tue, 12 Aug 2025 20:46:04 +0000 Received: from desiato.infradead.org ([2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1ulsrk-0000000Bb96-45pB for linux-arm-kernel@bombadil.infradead.org; Tue, 12 Aug 2025 17:32:52 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Content-Transfer-Encoding:Content-Type :In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date:Message-ID: Sender:Reply-To:Content-ID:Content-Description; bh=QOg1TD8bTIja1jsfCfz0y6W3vB735g3sOL05FkDgwYo=; b=OemYQLHAEZuB4y/H9r9o/At0Ae mXPG9Uz/6IzNypllTRvE824zIZdBmXksukJr2qSgPFC6aEto2iTygZRBS2LMlwtj3dMwry9GU2Ffp zXUVEDRD7bl0/oqaCPzjtd3xNR0Gu9ZrEbFVXuDAbUuexA5T/aKCO6IzdaRLxO3POe1hTeDzYMrPM mv7Jb/eqZ7CRyZX20K+3/xK9Xl1bI7trLqpxX1fTT/lw8W6AHxQnwnvZdd5/drPF4amiBenYkW1i+ O2ZRTHRm3PamAAXtCgIjxmHiLYWWo07XqnM7MevrU4wb/vtddqiBPcIuVMLZe8LPfRrgFX4rNIIW5 zYC7Bmkw==; Received: from foss.arm.com ([217.140.110.172]) by desiato.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1ulsrZ-0000000FsKe-1pdn for linux-arm-kernel@lists.infradead.org; Tue, 12 Aug 2025 17:32:44 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BAD9C24E9; Tue, 12 Aug 2025 10:32:30 -0700 (PDT) Received: from [192.168.20.57] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id EA0903F63F; Tue, 12 Aug 2025 10:32:36 -0700 (PDT) Message-ID: <2d9259e4-1b58-435d-bf02-9c4badd52fd9@arm.com> Date: Tue, 12 Aug 2025 12:32:36 -0500 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] arm64: defconfig: enable CONFIG_SCHED_CLUSTER To: "Christoph Lameter (Ampere)" Cc: Huang Shijie , catalin.marinas@arm.com, will@kernel.org, patches@amperecomputing.com, Shubhang@os.amperecomputing.com, krzysztof.kozlowski@linaro.org, bjorn.andersson@oss.qualcomm.com, geert+renesas@glider.be, arnd@arndb.de, nm@ti.com, ebiggers@kernel.org, nfraprado@collabora.com, prabhakar.mahadev-lad.rj@bp.renesas.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org References: <20250808025533.6422-1-shijie@os.amperecomputing.com> Content-Language: en-US From: Jeremy Linton In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250812_183241_897487_3AB72607 X-CRM114-Status: GOOD ( 17.19 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 8/12/25 11:33 AM, Christoph Lameter (Ampere) wrote: > On Mon, 11 Aug 2025, Jeremy Linton wrote: > >> From what I've seen, SCHED_CLUSTER seems to be a bit of give and take >> depending on benchmark and machine. I'm not sure if it should be default >> enabled or not, but it would really be nice to have at least a larger sweep of >> benchmarks/machines in order to be sure of the decision. > > If the hardware provides a clusterid then I think this clusterid should be > used for the sched domains. CONFIG_SCHED_CLUSTER does that. So it should > be the default. Hi, The problem is that this information is being sourced from the ACPI PPTT. The ACPI specification (AFAIK) doesn't define a cluster, so the linux cluster information is being 'invented' based on however the firmware vendor choose to group CPU nodes in the PPTT. Which means its possible for them to unknowingly create clusters, or also fail to create them when they make sense. > > If there is no cluster information then these domains should not be > created. I think that is already the case? > >