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 8F92CC433EF for ; Fri, 20 May 2022 13:01:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=JXoCgYa9lpzoySnBYFGTMN0jX722Q0XtIcLm0uNqtH8=; b=HAa80k17dCqP41 S7FCGjE/ub76zQKy6pMQJsVTEmi+GMAWp8ThX87YV/t0WfVrylMIwylfgsoXL2tIEMp4P9GQFj0Y7 bdd3YV/ZyW6ELLRazrjQGWvXy3iHbHjVAJacC54WyTrxEJOAda5GBd8AwwiP8r+n7eDJ9g/UP9iwa Q4xXh4r43/ar2ADAymm25OCoPcF9U0SXkvU3T/Gi5g5ks1QzJKlUWsVPYzG0zcfAW/w2wYaTUQLEz nU3W4w6lJAgVno5oG/T8qlTWcqj8gjkdPQJ5cGVaqRMtEt9CsLXyCW7JArr8nspn9xp2Fsqh6Pa5h 1VuNVklKPe6vqH7fIFCw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ns2Em-00CXCz-Vq; Fri, 20 May 2022 13:00:13 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ns2Ej-00CXBi-DB; Fri, 20 May 2022 13:00:11 +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 50D731477; Fri, 20 May 2022 06:00:08 -0700 (PDT) Received: from bogus (unknown [10.57.66.157]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id ECDCE3F73D; Fri, 20 May 2022 06:00:05 -0700 (PDT) Date: Fri, 20 May 2022 13:59:59 +0100 From: Sudeep Holla To: Rob Herring Cc: Atish Patra , "linux-kernel@vger.kernel.org" , Atish Patra , Sudeep Holla , Vincent Guittot , Morten Rasmussen , Dietmar Eggemann , Qing Wang , linux-arm-kernel , linux-riscv Subject: Re: [PATCH v2 8/8] arch_topology: Add support to build llc_sibling on DT platforms Message-ID: <20220520125959.wlxz53cfqldljxjy@bogus> References: <20220518093325.2070336-1-sudeep.holla@arm.com> <20220518093325.2070336-9-sudeep.holla@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220520_060009_572055_D843C956 X-CRM114-Status: GOOD ( 21.70 ) 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: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, May 19, 2022 at 01:10:51PM -0500, Rob Herring wrote: > On Wed, May 18, 2022 at 4:34 AM Sudeep Holla wrote: > > > > ACPI PPTT provides cache identifiers and especially the last level cache > > identifier is used in obtaining last level cache siblings amongst CPUs. > > > > While we have the cpu map representing all the CPUs sharing last level > > cache in the cacheinfo driver, it is populated quite late in the boot > > while the information is needed to build scheduler domains quite early. > > Late is because it's a device_initcall() rather than late in the cpu > hotplug state machine, right? Right. The expectation is to run in on each online CPU in CPU hotplug state machine for some architectures. We may not need that on arm64 especially since we get all info from DT or ACPI, but e.g. x86 uses cpuid which needs to be executed on that CPU. > The late aspect is for sysfs presumably,but I think we could decouple that. OK, not sure when this sched_domain info is actually needed. It think it could be decoupled if we can wait until all the cpus are online. > Do all the firmware cache parsing early and then populate the sysfs parts > later. Yes that may work on DT/ACPI based systems, as I said x86 relies on cpuid. > It's not a unique problem as the DT unflattening and init code has to > do the same thing. I'd assume the hotplug and cpu sysfs devices have > to deal with the same thing. > OK, I will take a look at how to do that. -- Regards, Sudeep _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel