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 X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1A0FAC4321A for ; Thu, 25 Apr 2019 15:31:59 +0000 (UTC) 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 mail.kernel.org (Postfix) with ESMTPS id 4B4B42081C for ; Thu, 25 Apr 2019 15:31:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="Umv1qwXL" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 4B4B42081C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject: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=kI673k0rE56Gq0h6SfznQRahYJUOdMl0sFoN4lo37oU=; b=Umv1qwXL3XluZp 1yzNo8pQ1xj5JKaUK0A4KMbQTHxqGzfOXg7KcLe4Vv0NSVt8PVD7JGafmYGkSyBSOCnXff7g9owa/ M9z67Jr8SBgvkSgB9jn/yrY0BPgDo0cw+9Yvo+zRwQujG4B/t8vLN86wGpyaToATZO0TDwVdmPHGQ SpEqKDfZ3SqClRTzK6xXWKzsJB0Ru04u9HXYQRfpdB+cvu8argmHXTktYeK+0CEKSJTqS57LZrQJU Hwemm9YlypAzrKeSdf/doOBl3alX+yhgA8cvgJKjOASdBRHd1HSo97EN6wAxayrBguGz9+zpPRNPN VCfiAOaa6twWPyfmJZVA==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hJgLl-0005n5-O8; Thu, 25 Apr 2019 15:31:49 +0000 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70] helo=foss.arm.com) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1hJgLi-0005mW-8j for linux-arm-kernel@lists.infradead.org; Thu, 25 Apr 2019 15:31:47 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B20D4A78; Thu, 25 Apr 2019 08:31:45 -0700 (PDT) Received: from fuggles.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id CAC243F557; Thu, 25 Apr 2019 08:31:40 -0700 (PDT) Date: Thu, 25 Apr 2019 16:31:38 +0100 From: Will Deacon To: Michal Hocko Subject: Re: [PATCH] arm64: configurable sparsemem section size Message-ID: <20190425153138.GC25193@fuggles.cambridge.arm.com> References: <20190423203843.2898-1-pasha.tatashin@soleen.com> <20190425152550.GY12751@dhcp22.suse.cz> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190425152550.GY12751@dhcp22.suse.cz> User-Agent: Mutt/1.11.1+86 (6f28e57d73f2) () X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190425_083146_315054_958D52B7 X-CRM114-Status: GOOD ( 18.51 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: tiwai@suse.de, catalin.marinas@arm.com, dave.hansen@linux.intel.com, keith.busch@intel.com, linux-mm@kvack.org, baiyaowei@cmss.chinamobile.com, zwisler@kernel.org, sashal@kernel.org, dave.jiang@intel.com, linux-nvdimm@lists.01.org, vishal.l.verma@intel.com, jmorris@namei.org, ying.huang@intel.com, bp@suse.de, thomas.lendacky@amd.com, Pavel Tatashin , marc.zyngier@arm.com, jglisse@redhat.com, rppt@linux.vnet.ibm.com, bhelgaas@google.com, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org, ard.biesheuvel@linaro.org, sboyd@kernel.org, linux-kernel@vger.kernel.org, james.morse@arm.com, andrew.murray@arm.com, akpm@linux-foundation.org, fengguang.wu@intel.com Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Apr 25, 2019 at 05:25:50PM +0200, Michal Hocko wrote: > On Tue 23-04-19 16:38:43, Pavel Tatashin wrote: > > sparsemem section size determines the maximum size and alignment that > > is allowed to offline/online memory block. The bigger the size the less > > the clutter in /sys/devices/system/memory/*. On the other hand, however, > > there is less flexability in what granules of memory can be added and > > removed. > > > > Recently, it was enabled in Linux to hotadd persistent memory that > > can be either real NV device, or reserved from regular System RAM > > and has identity of devdax. > > > > The problem is that because ARM64's section size is 1G, and devdax must > > have 2M label section, the first 1G is always missed when device is > > attached, because it is not 1G aligned. > > > > Allow, better flexibility by making section size configurable. > > Is there any inherent reason (64k page size?) that enforces such a large > memsection? I gave *vague* memories of running out of bits in the page flags if we changed this, but that was a while back. If that's no longer the case, then I'm open to changing the value, but I really don't want to expose it as a Kconfig option as proposed in this patch. People won't have a clue what to set and it doesn't help at all with the single-Image effort. Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel