From: Christoph Hellwig <hch@infradead.org>
To: "Christian König" <christian.koenig@amd.com>
Cc: Christoph Hellwig <hch@infradead.org>,
wangtao <tao.wangtao@honor.com>,
sumit.semwal@linaro.org, kraxel@redhat.com,
vivek.kasireddy@intel.com, viro@zeniv.linux.org.uk,
brauner@kernel.org, hughd@google.com, akpm@linux-foundation.org,
amir73il@gmail.com, benjamin.gaignard@collabora.com,
Brian.Starkey@arm.com, jstultz@google.com, tjmercier@google.com,
jack@suse.cz, baolin.wang@linux.alibaba.com,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org,
linux-fsdevel@vger.kernel.org, linux-mm@kvack.org,
bintian.wang@honor.com, yipengxiang@honor.com,
liulu.liu@honor.com, feng.han@honor.com
Subject: Re: [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range
Date: Tue, 3 Jun 2025 06:19:38 -0700 [thread overview]
Message-ID: <aD72alIxu718uri4@infradead.org> (raw)
In-Reply-To: <09c8fb7c-a337-4813-9f44-3a538c4ee8b1@amd.com>
On Tue, Jun 03, 2025 at 03:14:20PM +0200, Christian König wrote:
> On 6/3/25 15:00, Christoph Hellwig wrote:
> > This is a really weird interface. No one has yet to explain why dmabuf
> > is so special that we can't support direct I/O to it when we can support
> > it to otherwise exotic mappings like PCI P2P ones.
>
> With udmabuf you can do direct I/O, it's just inefficient to walk the
> page tables for it when you already have an array of all the folios.
Does it matter compared to the I/O in this case?
Either way there has been talk (in case of networking implementations)
that use a dmabuf as a first class container for lower level I/O.
I'd much rather do that than adding odd side interfaces. I.e. have
a version of splice that doesn't bother with the pipe, but instead
just uses in-kernel direct I/O on one side and dmabuf-provided folios
on the other.
next prev parent reply other threads:[~2025-06-03 13:19 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-06-03 9:52 [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range wangtao
2025-06-03 9:52 ` [PATCH v4 1/4] fs: allow cross-FS copy_file_range for memory file with direct I/O wangtao
2025-06-03 10:56 ` Amir Goldstein
2025-06-03 12:38 ` wangtao
2025-06-03 12:43 ` Amir Goldstein
2025-06-03 9:52 ` [PATCH v4 2/4] dmabuf: Implement copy_file_range callback for dmabuf direct I/O prep wangtao
2025-06-03 10:42 ` Christian König
2025-06-03 12:26 ` wangtao
2025-06-03 13:04 ` Christoph Hellwig
2025-06-03 9:52 ` [PATCH v4 3/4] udmabuf: Implement udmabuf direct I/O wangtao
2025-06-03 9:52 ` [PATCH v4 4/4] dmabuf:system_heap Implement system_heap dmabuf " wangtao
2025-06-03 13:00 ` [PATCH v4 0/4] Implement dmabuf direct I/O via copy_file_range Christoph Hellwig
2025-06-03 13:14 ` Christian König
2025-06-03 13:19 ` Christoph Hellwig [this message]
2025-06-03 14:18 ` Christian König
2025-06-03 14:28 ` Christoph Hellwig
2025-06-03 15:55 ` Christian König
2025-06-03 16:01 ` Christoph Hellwig
2025-06-06 9:59 ` wangtao
2025-06-06 9:52 ` wangtao
2025-06-06 11:20 ` Christian König
2025-06-09 4:35 ` Christoph Hellwig
2025-06-09 9:32 ` wangtao
2025-06-10 10:52 ` Christian König
2025-06-10 13:37 ` Christoph Hellwig
2025-06-13 9:43 ` wangtao
2025-06-16 5:24 ` Christoph Hellwig
2025-06-10 13:34 ` Christoph Hellwig
2025-06-13 9:33 ` wangtao
2025-06-16 5:25 ` Christoph Hellwig
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