RFC-CorgiPile

[DoubleNorth]

Stochastic Gradient Descent (SGD) and SGD-like methods (e.g., Adam) are commonly used in PyTorch to train ML models. However, these methods rely on random data order to converge, which usually require a full data shuffle, leading to low I/O performance for disk-based storage.

We proposed a simple but novel two-level data shuffling strategy named CorgiPile (https://link.springer.com/article/10.1007/s00778-024-00845-0), which can avoid a full data shuffle while maintaining comparable convergence rate as if a full shuffle were performed. CorgiPile first samples and shuffles data at the block-level, and then shuffles data at the tuple-level within the sampled data blocks, i.e., firstly shuffling data blocks, and then merging sampled blocks in a small buffer, and finally shuffling tuples in the buffer for SGD. We have implemented CorgiPile inside PyTorch (https://github.com/DS3Lab/CorgiPile-PyTorch), and extensive experimental results show that our CorgiPile can achieve comparable convergence rate with the full-shuffle based SGD, and faster than PyTorch with full data shuffle.

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