multi gpu training.
### Feature request

What we can do if using run_clm.py to train with multi gpu's?


### Motivation

multi gpu training for faster training.

### Your contribution

can we add this in the script?
model = nn.DataParallel(model,device_ids=[i for i in range(torch.cuda.device_count())])
If you have multiple GPUs it will run on multiple GPUs.<|||||>![image](https://user-images.githubusercontent.com/41872440/216619913-99568f8c-8a82-42ab-ae7a-dd56846dd395.png)
I have 8 gpu's in this machine.
![image](https://user-images.githubusercontent.com/41872440/216619996-7af22496-7fb8-4b6d-90f2-3606846b3cdc.png)
I think its not taking all 8 gpu's. Already tried changing batch_sizes and with multiple of 8