Model saving results in a small size checkpoint

Hi Community

I am trying to save a checkpoint in a costume Model using model.save_pretrained() after each epoch. the .bin directory however will contain a config and weights file, the weights file is only 98 MB no matter how big or small I change the configs and the data size. At the same time, saving the model using results in a reasonable pth file that would be around 600MB. is there any requirements or extra parameters to use for the save_pretrained() function?

Hard to say anything without looking at the code. Could you post a small code snippet?