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arXiv · 2404.01847

Accelerating Transformer Pre-training with 2:4 Sparsity

Yuezhou Hu·Kang Zhao·Weiyu Huang·Jianfei Chen·Jun Zhu
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Abstract

Training large transformers is slow, but recent innovations on GPU architecture give us an advantage. NVIDIA Ampere GPUs can execute a fine-grained 2:4 sparse matrix multiplication twice as fast as its dense equivalent. In the light of this property, we comprehensively investigate the feasibility of accelerating feed-forward networks (FFNs) of transformers in pre-training. First, we define a ``flip rate'' to monitor the stability of a 2:4 training process. Utilizing this metric, we propose three techniques to preserve accuracy: to modify the sparse-refined straight-through estimator by applying the masked decay term on gradients, to determine a feasible decay factor in warm-up stage, and to enhance the model's quality by a dense fine-tuning procedure near the end of pre-training. Besides, we devise two techniques to practically accelerate training: to calculate transposable 2:4 masks by convolution, and to accelerate gated activation functions by reducing GPU L2 cache miss. Experiments show that our 2:4 sparse training algorithm achieves similar convergence to dense training algorithms on several transformer pre-training tasks, while actual acceleration can be observed on different shapes of transformer block apparently. Our toolkit is available at https://github.com/huyz2023/2by4-pretrain.

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BibTeXRIS

Yuezhou Hu, Kang Zhao, Weiyu Huang, Jianfei Chen, Jun Zhu. 2024-10-27. Accelerating Transformer Pre-training with 2:4 Sparsity. https://arxiv.org/abs/2404.01847

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