Re: [PATCH v16 0/4] RDMA: Add dma-buf support

[John Hubbard <jhubbard@nvidia.com>]

On 12/15/20 1:27 PM, Jianxin Xiong wrote:
> This patch series adds dma-buf importer role to the RDMA driver in
> attempt to support RDMA using device memory such as GPU VRAM. Dma-buf is
> chosen for a few reasons: first, the API is relatively simple and allows
> a lot of flexibility in implementing the buffer manipulation ops.
> Second, it doesn't require page structure. Third, dma-buf is already
> supported in many GPU drivers. However, we are aware that existing GPU
> drivers don't allow pinning device memory via the dma-buf interface.
> Pinning would simply cause the backing storage to migrate to system RAM.
> True peer-to-peer access is only possible using dynamic attach, which
> requires on-demand paging support from the NIC to work. For this reason,
> this series only works with ODP capable NICs.

Hi,

Looking ahead to after this patchset is merged...

Are there design thoughts out there, about the future of pinning to vidmem,
for this? It would allow a huge group of older GPUs and NICs and such to
do p2p with this approach, and it seems like a natural next step, right?


thanks,
-- 
John Hubbard
NVIDIA