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b=NVP7T92Pj5R+HK68YWTI3qrBcBUb0GZRbnewWGJQtuo27h4NrcHddte6wcGbe9CVT FqNPkMzpCV+bRmWLpGm1TtehzRASpimiYHJnQooPVyyFvAK5rYmiAn1WMznr6j/DN3 jz7qO9umdyQBrlfi3b82BaWbGT9Ys1j/LC+uOdEiA9Pklf/ppNaMiJk6XlSFHWnJVV llajGYdXbKkxslYPfhqK2cDXw5D9+pq7+Iah66z+ShJFTf+tUKeD2KUk5fjpfpknx2 DAksopGPXcqzcxkwBDmadAT89hyJ5pr4j+hPUr0AbLCzv7JiyzmO7wF9QdP/+gYx+t PAV8ey1C+e5mA== Date: Thu, 20 Mar 2025 14:50:19 -0700 From: Luis Chamberlain To: Christoph Hellwig Cc: Keith Busch , Bart Van Assche , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, lsf-pc@lists.linux-foundation.org, david@fromorbit.com, leon@kernel.org, sagi@grimberg.me, axboe@kernel.dk, joro@8bytes.org, brauner@kernel.org, hare@suse.de, willy@infradead.org, djwong@kernel.org, john.g.garry@oracle.com, ritesh.list@gmail.com, p.raghav@samsung.com, gost.dev@samsung.com, da.gomez@samsung.com Subject: Re: [LSF/MM/BPF TOPIC] breaking the 512 KiB IO boundary on x86_64 Message-ID: References: <20250320141846.GA11512@lst.de> <20250320163804.GA21242@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250320163804.GA21242@lst.de> X-Rspamd-Queue-Id: 1C0F2C0006 X-Rspamd-Server: rspam05 X-Rspam-User: X-Stat-Signature: w4efn15s7whew4n8duuwmkm6ww5coaee X-HE-Tag: 1742507421-271629 X-HE-Meta: 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 iAJ/OSfo dqx5shQjo5cunnHbzOwLTiAiVz0tyhV7HJCPa X-Bogosity: Ham, tests=bogofilter, spamicity=0.000002, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, Mar 20, 2025 at 05:38:04PM +0100, Christoph Hellwig wrote: > On Thu, Mar 20, 2025 at 09:58:47AM -0600, Keith Busch wrote: > > I allocate out of hugetlbfs to reliably send direct IO at this size > > because the nvme driver's segment count is limited to 128. > > It also works pretty well for buffered I/O for file systems supporting > larger folios. I can trivially create 1MB folios in the page cache > on XFS and then do I/O on them. Right, but try DIO or io-uring cmd. The two step dma API seems to help us bridge this gap and provide parity. Luis