On Thu, Feb 4, 2021 at 2:48 AM John Hubbard <jhubbard@xxxxxxxxxx> wrote: > > 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? The argument is that vram is a scarce resource, but I don't know if that is really the case these days. At this point, we often have as much vram as system ram if not more. Alex
