[FIXED] When would I use model.to("cuda:1") as opposed to model.to("cuda:0")?

Issue

I have a user with two GPU's; the first one is AMD which can't run CUDA, and the second one is a cuda-capable NVIDIA GPU. I am using the code model.half().to("cuda:0"). I'm not sure if the invocation successfully used the GPU, nor am I able to test it because I don't have any spare computer with more than 1 GPU lying around.

In this case, does "cuda:0" mean the first device which can run CUDA, so it would've worked even if their first device was AMD? Or would I need to say "cuda:1" instead? How would I detect which number is the first CUDA-capable device?

Solution

I tested it and as I suspected the model.half().to("cuda:0") will put your model in the first available GPU with CUDA support i.e. NVIDIA GPU in your case, the AMD GPU isn't visible as a cuda device, feel safe to assume cuda:0 is only a CUDA enabled GPU, and AMD GPU won't be seen by your program. Have a good day.

Answered By - mak13