List Available GPUs

In Pytorch, you can list number of available GPUs using torch.cuda.device_count().

• If you specify cpu as a device such as torch.device("cpu"), this means all available CPUs/cores and memory will be used in the computation of tensors.
• If you specify cuda as a device such as torch.device("cuda"), it is the same as torch.device("cuda:0") which is the first GPU and memory.
• Otherwise, specify which GPU you want using torch.device(f"cuda:{i}") for the ith device.