From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96D20190072; Thu, 20 Mar 2025 21:50:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742507421; cv=none; b=IQmy08yKW4sEieRFjRcZw+bhrSUrv2poQ1nktb64XDPQeAwcIbDf+GdWqVtcM6ukAKr8ZxV2qvU6Gyn+/CKF5qhRNDZrdHieaQUgsY79xrSwcn7dTnjURKJva8ghux0qNJJLgN6XZvOKLGtqczqM1mhLHuWJvbvXal1qZIU4O/0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742507421; c=relaxed/simple; bh=CdqCAE+cs4te1+LSwC83I+ZwB5sHxeVNxfaz1e4os/w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=CZ/B98Px9Hidhv/m2s/dQu/UOI8GvZHopL7kjey3WYol7vBSVyzlXqAOiqDptuGeYGkwMHfQRe9cDofb8RyfcfYhlLhK312sYhTx3dkfLXpTzJMhmGrr7uiLgiaPPjKw08+2L7N8vKaU26l2TybEotWoq13HLSyLZFC9zW5Gn/4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=NVP7T92P; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="NVP7T92P" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8923CC4CEDD; Thu, 20 Mar 2025 21:50:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1742507421; bh=CdqCAE+cs4te1+LSwC83I+ZwB5sHxeVNxfaz1e4os/w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; 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> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250320163804.GA21242@lst.de> 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