Loading GPU trained checkpoint to cuda device doesn't utilise GPU for testing

Have trained a U-Net model for image segmentation on my win64 environment with:
Python 3.8.13
CUDA Version: 11.3
PyTorch Version: 1.12.1
PyTorch Lightning Version: 1.5.10

I saved the checkpoint files and the training fully utilised my GPU.
It took about 2hrs per epoch to train the model.

I then loaded my model from the final checkpoint and used map_location=torch.device(‘cuda’) .
I then ran the test , using pytorch lighting Trainer.test().

Estimated time for 1 epoch 58hrs.
The GPU Cuda is 0% but the copy area on the card is at 80% constantly.

Not sure what is happening.
Probably a newbie issue :face_with_diagonal_mouth: but any insight most appreciated!

Hi, the map location only specify where the weights are loaded. When you isntantiate the model, it uses those or a copy of those depending on where the model is allocated.

If you are using plain pytorch you should allocate the model in the gpu as:
if you use pytorch lightning you have to pass the same kwarg as for training when you build the trainer.
This is gpus=1 (or more)
Also note that if you use pytorch lightning, they handle the model loading by passing

1 Like

Thankyou Juan. Appreciate the quick response. :+1:

I’m passing the checkpoint file location to the trainer and the same kwargs …however I’ll double check all the args just to be sure!