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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (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 AA349C3DA4A for ; Fri, 16 Aug 2024 23:43:38 +0000 (UTC) Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=127.0.0.1 Received: from boromir.ozlabs.org (localhost [127.0.0.1]) by lists.ozlabs.org (Postfix) with ESMTP id 4Wlz8T2b4Sz2ysb; Sat, 17 Aug 2024 09:43:37 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: lists.ozlabs.org; arc=none smtp.remote-ip=217.140.110.172 Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=arm.com (client-ip=217.140.110.172; helo=foss.arm.com; envelope-from=dietmar.eggemann@arm.com; receiver=lists.ozlabs.org) Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lists.ozlabs.org (Postfix) with ESMTP id 4WlmmC0GX1z2xXV for ; Sat, 17 Aug 2024 01:55:22 +1000 (AEST) 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 06F1613D5; Fri, 16 Aug 2024 08:55:17 -0700 (PDT) Received: from [192.168.181.244] (usa-sjc-mx-foss1.foss.arm.com [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 931F53F58B; Fri, 16 Aug 2024 08:54:46 -0700 (PDT) Message-ID: <9c46d5f0-f4ff-461b-b483-840fab6dfecc@arm.com> Date: Fri, 16 Aug 2024 17:54:39 +0200 X-Mailing-List: linuxppc-dev@lists.ozlabs.org List-Id: List-Help: List-Post: List-Subscribe: , , List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 1/4] cpu/SMT: Provide a default topology_is_primary_thread() To: Yicong Yang , catalin.marinas@arm.com, will@kernel.org, sudeep.holla@arm.com, tglx@linutronix.de, peterz@infradead.org, mpe@ellerman.id.au, linux-arm-kernel@lists.infradead.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com Cc: linuxppc-dev@lists.ozlabs.org, x86@kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, rafael@kernel.org, jonathan.cameron@huawei.com, prime.zeng@hisilicon.com, linuxarm@huawei.com, yangyicong@hisilicon.com, xuwei5@huawei.com, guohanjun@huawei.com References: <20240806085320.63514-1-yangyicong@huawei.com> <20240806085320.63514-2-yangyicong@huawei.com> From: Dietmar Eggemann Content-Language: en-US In-Reply-To: <20240806085320.63514-2-yangyicong@huawei.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 06/08/2024 10:53, Yicong Yang wrote: > From: Yicong Yang > > Currently if architectures want to support HOTPLUG_SMT they need to > provide a topology_is_primary_thread() telling the framework which > thread in the SMT cannot offline. However arm64 doesn't have a > restriction on which thread in the SMT cannot offline, a simplest > choice is that just make 1st thread as the "primary" thread. So > just make this as the default implementation in the framework and > let architectures like x86 that have special primary thread to > override this function. IMHO, ARM64 (/ARM), RISCV and PARISC (SMP) use GENERIC_ARCH_TOPOLOGY (and drivers/base/arch_topology.c) so they could share topology_is_primary_thread() also there? [...]