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Bottomley" , Helge Deller , Andreas Larsson , Jesper Dangaard Brouer , Ilias Apalodimas , Steven Rostedt , Masami Hiramatsu , Mathieu Desnoyers , Arnd Bergmann , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Steffen Klassert , Herbert Xu , David Ahern , Willem de Bruijn , Shuah Khan , Sumit Semwal , Christian =?iso-8859-1?Q?K=F6nig?= , Amritha Nambiar , Maciej Fijalkowski , Alexander Mikhalitsyn , Kaiyuan Zhang , Christian Brauner , Simon Horman , David Howells , Florian Westphal , Yunsheng Lin , Kuniyuki Iwashima , Jens Axboe , Arseniy Krasnov , Aleksander Lobakin , Michael Lass , Jiri Pirko , Sebastian Andrzej Siewior , Lorenzo Bianconi , Richard Gobert , Sridhar Samudrala , Xuan Zhuo , Johannes Berg , Abel Wu , Breno Leitao , David Wei , Shailend Chand , Harshitha Ramamurthy , Shakeel Butt , Jeroen de Borst , Praveen Kaligineedi Subject: Re: [RFC PATCH net-next v8 02/14] net: page_pool: create hooks for custom page providers Message-ID: References: <20240507164838.GG4718@ziepe.ca> <0d5da361-cc7b-46e9-a635-9a7a4c208444@gmail.com> <20240507175644.GJ4718@ziepe.ca> <6a50d01a-b5b9-4699-9d58-94e5f8f81c13@gmail.com> <20240507233247.GK4718@ziepe.ca> <1e2823db-504b-4829-856f-3f45a45ccada@gmail.com> <8ced4c49-d153-40fb-9e62-0a5784cfa864@gmail.com> Precedence: bulk X-Mailing-List: linux-kselftest@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: <8ced4c49-d153-40fb-9e62-0a5784cfa864@gmail.com> X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html On Wed, May 08, 2024 at 06:02:14PM +0100, Pavel Begunkov wrote: > Well, the example fell flat, but you don't use dmabuf when there are > no upsides from using it. For instance, when you already have pinned > pages, you're going to use pages, and there are no other refcounting > concerns. Sure. > Unless there is an advantage of dmabufs over FOLL_LONGTERM > that I don't know about when used with normal user pages. The advantages of using a dma-buf over FOLL_LONGTERM are: a) you pre-dma map, which is a significant performance advantage for IOMMU-based setups b) you support any dma-buf exported and not just user memory. This is primarily important for PCIe P2P, but there might be other useful exporters as well > > wish io_uring would have just implemented them from the start instead of > > the current fixed buffers that are not quite as useful by not > > pre-mapping DMA and not supporting P2P. > > fdget(dmabuf) would be horrible, I assume that's not the suggestion. I'm not even sure what you mean with that.