@ptrblck So I easily should just add:
model = Model(input_size, output_size)
if torch.cuda.device_count() > 1:
  print("Let's use", torch.cuda.device_count(), "GPUs!")
  # dim = 0 [30, xxx] -> [10, ...], [10, ...], [10, ...] on 3 GPUs
  model = nn.DataParallel(model)

model.to(device)

to my code and that is it?
BTW the out put of that command in my system is:
("Let's use",3L,'GPUs!')


I am not sure what is the meaning of L after 3, but i guess that is no biggi for now, i understood what it means…
One more question.
Lets say I have 3GPUs but I just want to use 2 of them. how should i specify that?