How to use multi-gpu to train nerf?

[ThePrecoder]

[Gword]

Jnerf has not been tested on multi-gpu. You can try it according to the Jittor MPI tutorial. If you encounter any problems, please contact us.

[qingxu-thu]

I have tried mpi but find out that some operator in ray_smapler can not support mpicc, like item() and coords_out.sync(). I try to fix it but it might refer to other files I'm not sure that I can fix the problems.