From: Jason Gunthorpe <jgg@nvidia.com>
To: Pavel Begunkov <asml.silence@gmail.com>
Cc: linux-block@vger.kernel.org, io-uring <io-uring@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"Gohad, Tushar" <tushar.gohad@intel.com>,
"Christian König" <christian.koenig@amd.com>,
"Christoph Hellwig" <hch@lst.de>,
"Kanchan Joshi" <joshi.k@samsung.com>,
"Anuj Gupta" <anuj20.g@samsung.com>,
"Nitesh Shetty" <nj.shetty@samsung.com>,
"lsf-pc@lists.linux-foundation.org"
<lsf-pc@lists.linux-foundation.org>
Subject: Re: [LSF/MM/BPF TOPIC] dmabuf backed read/write
Date: Thu, 5 Feb 2026 13:41:35 -0400 [thread overview]
Message-ID: <20260205174135.GA444713@nvidia.com> (raw)
In-Reply-To: <4796d2f7-5300-4884-bd2e-3fcc7fdd7cea@gmail.com>
On Tue, Feb 03, 2026 at 02:29:55PM +0000, Pavel Begunkov wrote:
> The proposal consists of two parts. The first is a small in-kernel
> framework that allows a dma-buf to be registered against a given file
> and returns an object representing a DMA mapping.
What is this about and why would you need something like this?
The rest makes more sense - pass a DMABUF (or even memfd) to iouring
and pre-setup the DMA mapping to get dma_addr_t, then directly use
dma_addr_t through the entire block stack right into the eventual
driver.
> Tushar was helping and mention he got good numbers for P2P transfers
> compared to bouncing it via RAM.
We can already avoid the bouncing, it seems the main improvements here
are avoiding the DMA map per-io and allowing the use of P2P without
also creating struct page. Meanginful wins for sure.
Jason
next prev parent reply other threads:[~2026-02-05 17:41 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CGME20260204153051epcas5p1c2efd01ef32883680fed2541f9fca6c2@epcas5p1.samsung.com>
2026-02-03 14:29 ` [LSF/MM/BPF TOPIC] dmabuf backed read/write Pavel Begunkov
2026-02-03 18:07 ` Keith Busch
2026-02-04 6:07 ` Anuj Gupta/Anuj Gupta
2026-02-04 11:38 ` Pavel Begunkov
2026-02-04 15:26 ` Nitesh Shetty
2026-02-05 3:12 ` Ming Lei
2026-02-05 18:13 ` Pavel Begunkov
2026-02-05 17:41 ` Jason Gunthorpe [this message]
2026-02-05 19:06 ` Pavel Begunkov
2026-02-05 23:56 ` Jason Gunthorpe
2026-02-06 15:08 ` Pavel Begunkov
2026-02-06 15:20 ` Jason Gunthorpe
2026-02-06 17:57 ` Pavel Begunkov
2026-02-06 18:37 ` Jason Gunthorpe
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