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 CD278C30658 for ; Tue, 2 Jul 2024 11:52:21 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4WD1VX3rMbz3g57 for ; Tue, 2 Jul 2024 21:52:20 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=lst.de (client-ip=213.95.11.211; helo=verein.lst.de; envelope-from=hch@lst.de; receiver=lists.ozlabs.org) Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4WD1V53CKyz3fy7 for ; Tue, 2 Jul 2024 21:51:57 +1000 (AEST) Received: by verein.lst.de (Postfix, from userid 2407) id D343968AA6; Tue, 2 Jul 2024 13:51:51 +0200 (CEST) Date: Tue, 2 Jul 2024 13:51:51 +0200 From: Christoph Hellwig To: Alistair Popple Subject: Re: [PATCH 07/13] huge_memory: Allow mappings of PUD sized pages Message-ID: <20240702115151.GA16313@lst.de> References: <874j98gjfg.fsf@nvdebian.thelocal> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <874j98gjfg.fsf@nvdebian.thelocal> User-Agent: Mutt/1.5.17 (2007-11-01) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linmiaohe@huawei.com, nvdimm@lists.linux.dev, jack@suse.cz, David Hildenbrand , djwong@kernel.org, dave.hansen@linux.intel.com, david@fromorbit.com, peterx@redhat.com, linux-mm@kvack.org, will@kernel.org, hch@lst.de, dave.jiang@intel.com, vishal.l.verma@intel.com, linux-doc@vger.kernel.org, willy@infradead.org, jgg@ziepe.ca, catalin.marinas@arm.com, linux-ext4@vger.kernel.org, ira.weiny@intel.com, jhubbard@nvidia.com, npiggin@gmail.com, linux-cxl@vger.kernel.org, bhelgaas@google.com, dan.j.williams@intel.com, linux-arm-kernel@lists.infradead.org, tytso@mit.edu, linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, logang@deltatee.com Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, Jul 02, 2024 at 08:19:01PM +1000, Alistair Popple wrote: > > (B) As long as we have subpage mapcounts, this prevents vmemmap > > optimizations [1]. Is that only used for device-dax for now and are > > there no plans to make use of that for fs-dax? > > I don't have any plans to. This is purely focussed on refcounting pages > "like normal" so we can get rid of all the DAX special casing. > > > (C) We managed without so far :) > > Indeed, although Christoph has asked repeatedly ([1], [2] and likely > others) that this gets fixed and I finally got sick of it coming up > everytime I need to touch something with ZONE_DEVICE pages :) > > Also it removes the need for people to understand the special DAX page > recounting scheme and ends up removing a bunch of cruft as a bonus: > > 59 files changed, 485 insertions(+), 869 deletions(-) > > And that's before I clean up all the pgmap reference handling. It also > removes the pXX_trans_huge and pXX_leaf distinction. So we managed, but > things could be better IMHO. Yes. I can't wait for this series making the finish line. There might be more chance for cleanups and optimizations around ZONE_DEVICE, but this alone is a huge step forward.