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 AD07F13D531; Mon, 20 Jan 2025 14:22:21 +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=1737382941; cv=none; b=tDECKvTrEwCPE1F0zqdu+B8li7yjYo2oh0A6qjfIEWi4UW8kuy8znYQg756uM1cdMz3LGrXeOVuzBoHWfxJnFuvcGC7/l68mF3a9AaCP9o9MpBgjCh6lWT9HCTIFRE7PmUkYtSN/GkRz0FHwhaPO0x9kJ7JBaR2a7w3C5SALG7g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737382941; c=relaxed/simple; bh=Q/ah7Xad9Pkqp3TtguBsx5XKqUkR2Fz8GupvOx/hv9c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=hjYov7FU33SR04Bi6AxjqKa+1bXiugrKAwEohvOk1dZCt+zNLJUjWzloJIdUmaZ4clExck/V53EgDF0ThV9FmK49IO46B/prmKzMDDfbCHkp8N6f8ZdHVklsROgl6WjUa8BGJUE4026k2VxB+2alaHL9qQ+Df5r7hRkPWWwbBGI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=btF4+XTF; 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="btF4+XTF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1E5B3C4CEDD; Mon, 20 Jan 2025 14:22:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1737382941; bh=Q/ah7Xad9Pkqp3TtguBsx5XKqUkR2Fz8GupvOx/hv9c=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=btF4+XTFOp0ga6T7d+3J8b/geuEwFuwnlTi+lf83vRcdKRoTVfYz+j7wryq5Tg4lu ZK3w9rFFY3hmH8PuksePlIqesvWZnTUqA5jg6XYq0s3ob+luFv7MtS9OMUIw9Fb+d1 PpTguh1N6eFf7/CK1jWbCTnY1iq78Zvb3ZoUwJ2J9PeBxfNfaTQ1fh/lj/8M8/iUgY EHdLjEY/Swkp03kzxyfecr+1HAz3x7k6EHPdayAGuGa01d6bD/g5yKqk6R2xDjIVze ItO6SThpO9X9ifELiuv6JUqG2086TJNksTrRHaJ2VUjnGiHZkb8ogNz+vmlMHbJNkL Sy6xKQupyurPQ== Date: Mon, 20 Jan 2025 16:22:17 +0200 From: Leon Romanovsky To: David Howells Cc: lsf-pc@lists.linux-foundation.org, John Hubbard , Matthew Wilcox , brauner@kernel.org, Herbert Xu , linux-fsdevel@vger.kernel.org, linux-crypto@vger.kernel.org, linux-mm@kvack.org, linux-block@vger.kernel.org, Christoph Hellwig , Jason Gunthorpe Subject: Re: [LSF/MM/BPF TOPIC] Improving iov_iter - and replacing scatterlists Message-ID: <20250120142217.GA153811@unreal> References: <886959.1737148612@warthog.procyon.org.uk> Precedence: bulk X-Mailing-List: linux-fsdevel@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: <886959.1737148612@warthog.procyon.org.uk> On Fri, Jan 17, 2025 at 09:16:52PM +0000, David Howells wrote: > Hi, > > I'd like to propose a discussion of two things: firstly, how might we improve > iov_iter and, secondly, would it be possible to replace scatterlists. <...> > Rumour has it that John Hubbard may be working along similar lines, possibly > just in the area of bio_vecs and ITER_BVEC. > > > [*] Second: Can we replace the uses of scatterlist with iov_iter and reduce > the number of iterator classes we have? <...> I would say yes to the questions. Regarding rumors, I don't know, but Christoph, Jason and I are working towards this goal. We proposed new DMA API which doesn't need scatterlists and allows callers to implement their own data-structures. See this "[PATCH v6 00/17] Provide a new two step DMA mapping API" series https://lore.kernel.org/all/cover.1737106761.git.leon@kernel.org and its block layer followup "[RFC PATCH 0/7] Block and NMMe PCI use of new DMA mapping API" https://lore.kernel.org/all/cover.1730037261.git.leon@kernel.org Thanks