From: Jason Gunthorpe <jgg@ziepe.ca>
To: Jianxin Xiong <jianxin.xiong@intel.com>
Cc: linux-rdma@vger.kernel.org, Doug Ledford <dledford@redhat.com>,
Sumit Semwal <sumit.semwal@linaro.org>,
Leon Romanovsky <leon@kernel.org>
Subject: Re: [RFC PATCH 0/3] RDMA: Add dma-buf support
Date: Thu, 16 Apr 2020 14:54:54 -0300 [thread overview]
Message-ID: <20200416175454.GT5100@ziepe.ca> (raw)
In-Reply-To: <1587056973-101760-1-git-send-email-jianxin.xiong@intel.com>
On Thu, Apr 16, 2020 at 10:09:30AM -0700, Jianxin Xiong wrote:
> This patch set adds dma-buf importer role to the RDMA driver and thus
> provides a non-proprietary approach for supporting RDMA to/from buffers
> allocated from device local memory (e.g. GPU VRAM).
How exactly does this allow access to GPU VRAM?
dma_buf_attach() cannot return non-struct page memory in the sgt, and
I'm not sure the API has enough information to do use the p2pdma stuff
to even establish a p2p mapping.
We've already been over this in another thread.. There is a way to
improve things to get there, but I don't understand how this patch
series is claming to be able to work with VRAM - if it is that means
there is a bug in a GPU driver that should be squashed.
Other than that, this seems broadly reasonable to me as a way to
access a DMA buf pointing at system memory, though it would be nice to
have a rational for why we should do this rather than rely on mmap'd
versions of a dma buf.
Jason
next prev parent reply other threads:[~2020-04-16 17:54 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-16 17:09 [RFC PATCH 0/3] RDMA: Add dma-buf support Jianxin Xiong
2020-04-16 17:09 ` [RFC PATCH 1/3] RDMA/umem: Support importing dma-buf as user memory region Jianxin Xiong
2020-04-16 18:01 ` Jason Gunthorpe
2020-04-16 19:41 ` Xiong, Jianxin
2020-04-17 12:31 ` Jason Gunthorpe
2020-04-17 15:49 ` Xiong, Jianxin
2020-04-16 18:02 ` Leon Romanovsky
2020-04-16 18:04 ` Jason Gunthorpe
2020-04-16 18:30 ` Leon Romanovsky
2020-04-16 21:08 ` Xiong, Jianxin
2020-04-16 17:09 ` [RFC PATCH 2/3] RDMA/uverbs: Add uverbs commands for fd-based MR registration Jianxin Xiong
2020-04-16 17:47 ` Jason Gunthorpe
2020-04-16 18:32 ` Xiong, Jianxin
2020-04-17 12:35 ` Jason Gunthorpe
2020-04-16 17:09 ` [RFC PATCH 3/3] RDMA/mlx5: Support new uverbs commands for registering fd-based MR Jianxin Xiong
2020-04-16 17:54 ` Jason Gunthorpe [this message]
2020-04-16 19:08 ` [RFC PATCH 0/3] RDMA: Add dma-buf support Xiong, Jianxin
2020-04-16 19:34 ` Jason Gunthorpe
2020-04-16 21:02 ` Xiong, Jianxin
2020-04-17 12:35 ` Jason Gunthorpe
2020-04-17 16:49 ` Xiong, Jianxin
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