GPUDirect RDMA - use Jetson's DMA

Hi,
In the GPUDirect RDMA Github demo:

You use the FPGA’s DMA engine to copy the data from the GPU’s memory space into the FPGA memory.
Is it possible to use the Jetson’s DMA engine instead? That it will copy the data into the FPGA memory?

Thanks

Hi,

RDMA is about direct access, no memory copy is involved.

GPUDirect RDMA’s target is to share the cudaMalloc buffer with FPGA.
It can not used in the counterpart.

Thanks.

@AastaLLL
Thank you for your reply.

Just to make sure, what do you mean by “counterpart”?

Thanks

Hi,

FPGA can access CUDA memory.
But CUDA cannot access FPGA’s memory.

This requires importing/wrapping the CPU memory into GPU space.
Which is not supported.

Thanks.

Thank you for your reply @AastaLLL
There is something small I didn’t understand:

In the demo the FPGA can access CUDA memory.

“Someone” has to program the FPGA’s DMA engine with appropriate data:

  • physical source address, corresponds to CUDA virtual space
  • physical destination address, in the FPGA
  • length
  1. Who does this? - the CUDA code?
  2. Why he can’t program the Jetson DMA to do the same work instead of the FPGA DMA?

Thanks for the help

Hi,

Could you share the demo you mentioned with us?
So we can know more about the questions.

Thanks.

Sure: