I see. And if i set the USE_SYSTEM_NCCL flag, then would NCCL be linked dynamically or statically to pytorch?
To illustrate my intention, I want to know that if I need to recompile pytorch everytime I change something in my custom NCCL version. If its linked dynamically, then as long as I keep the same NCCL interface I do not need to recompile PyTorch.