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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <886959.1737148612@warthog.procyon.org.uk> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 75D1E80010 X-Stat-Signature: 5cdmn8n76r1mzyzyh8x93ptufb19js9a X-Rspam-User: X-HE-Tag: 1737382942-988859 X-HE-Meta: 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 YrGRZ6RJ DIzhNZSyUe8nA9v4NoObEkYkEAX5gwjc2ycz8fXIQvNKm35dEgnQurbPEtADqYg6gmHUktnhI0tdGdWiWAmiVm8ihBdsaE6D4qvI5cA5E/VnvFaadiS4fKpbmEysMMFyOkQLNIWOabBCfc5Qx1sIiyfnjbxoR/ld7AQv7mQjuc72BDYNe75hCl90gRJQnklhEFnR8aeMjK7dWBgfYwBOUFNtHQzpC5nuAnPgob7kCm56fNRuuKjNsezb3JpN4YCHqqO4uCcOOpUxTDbLrHGQKpmC1JFJaTNUoqmhOziafOW2jXM0mrzawxMeq87NTnq1MvEhP X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, 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 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