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PyTorch Checkpoint Format

Our large model-optimized checkpoint format is based off the standard HDF5 file format. At a high-level, when saving a checkpoint, the Cerebras stack will take a PyTorch state dictionary, flatten it, and store it in an HDF5 file. For example, the following state dictionary is flattened and stored into the H5 file as follows:
Flattened H5:
A model/optimizer state dictionary can be saved in the new checkpoint format using the cstorch.save method:
A checkpoint saved using the above can be loaded using the cstorch.load method:

Convert to Pickle Format

If using cstorch.load is not a sufficient solution for loading the checkpoint into memory, a simple conversion can be done to the pickle format: