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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 19AAAC3814E for ; Tue, 23 Aug 2022 08:13:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242249AbiHWINR (ORCPT ); Tue, 23 Aug 2022 04:13:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33302 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241998AbiHWIK1 (ORCPT ); Tue, 23 Aug 2022 04:10:27 -0400 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 511F8659EF for ; Tue, 23 Aug 2022 01:06:54 -0700 (PDT) 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 214E9113E; Tue, 23 Aug 2022 01:06:58 -0700 (PDT) Received: from localhost (ionvoi01-desktop.cambridge.arm.com [10.1.196.65]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 340EB3F718; Tue, 23 Aug 2022 01:06:54 -0700 (PDT) Date: Tue, 23 Aug 2022 09:06:52 +0100 From: Ionela Voinescu To: Yicong Yang Cc: sudeep.holla@arm.com, vincent.guittot@linaro.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, rafael@kernel.org, 21cnbao@gmail.com, jonathan.cameron@huawei.com, linuxarm@huawei.com, prime.zeng@huawei.com, yangyicong@hisilicon.com Subject: Re: [PATCH] arch_topology: Make cluster topology span at least SMT CPUs Message-ID: References: <20220823073044.58697-1-yangyicong@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220823073044.58697-1-yangyicong@huawei.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Yicong, On Tuesday 23 Aug 2022 at 15:30:44 (+0800), Yicong Yang wrote: > From: Yicong Yang > > Currently cpu_clustergroup_mask() will return CPU mask if cluster span > more or the same CPUs as cpu_coregroup_mask(). This will result topology > borken on non-Cluster SMT machines. Might be worth adding here:.. "when building with CONFIG_SCHED_CLUSTER=y" > I thought I had covered this case, but I think I had considered LLC spanning more than one core (tested on TX2 as well). So you'd only hit this if LLC and cluster level span the same cores (a single core in this case, for non-cluster), in the presence of SMT. Reviewed-by: Ionela Voinescu Many thanks, Ionela. > Test with: > qemu-system-aarch64 -enable-kvm -machine virt \ > -net none \ > -cpu host \ > -bios ./QEMU_EFI.fd \ > -m 2G \ > -smp 48,sockets=2,cores=12,threads=2 \ > -kernel $Image \ > -initrd $Rootfs \ > -nographic > -append "rdinit=init console=ttyAMA0 sched_verbose loglevel=8" > > We'll get below error: > [ 3.084568] BUG: arch topology borken > [ 3.084570] the SMT domain not a subset of the CLS domain > > Since cluster is a level higher than SMT, fix this by making cluster > spans at least SMT CPUs. > > Cc: Sudeep Holla > Cc: Vincent Guittot > Cc: Ionela Voinescu > Fixes: bfcc4397435d ("arch_topology: Limit span of cpu_clustergroup_mask()") > Signed-off-by: Yicong Yang > --- > drivers/base/arch_topology.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c > index 0424b59b695e..0056a1273275 100644 > --- a/drivers/base/arch_topology.c > +++ b/drivers/base/arch_topology.c > @@ -724,7 +724,7 @@ const struct cpumask *cpu_clustergroup_mask(int cpu) > */ > if (cpumask_subset(cpu_coregroup_mask(cpu), > &cpu_topology[cpu].cluster_sibling)) > - return get_cpu_mask(cpu); > + return cpu_smt_mask(cpu); > > return &cpu_topology[cpu].cluster_sibling; > } > -- > 2.24.0 >