SPION: Layer-Wise Sparse Training of Transformer via Convolutional Flood
  Filling
Bokyeong Yoon Yoonsang Han Gordon Euhyun Moon
Sparsifying the Transformer has garnered considerable interest, as training
the Transformer is very computationally demanding. Prior efforts to sparsify
the Transformer have either used a fixed pattern or data-driven approach to
reduce the number of operations involving the computation of multi-head
attention, which is the main bottleneck of the Transformer. However, existing
methods suffer from inevitable problems, such as the potential loss of
essential sequence features due to the uniform fixed pattern applied across all
layers, and an increase in the model size resulting from the use of additional
parameters to learn sparsity patterns in attention operations. In this paper,
we propose a novel sparsification scheme for the Transformer that integrates
convolution filters and the flood filling method to efficiently capture the
layer-wise sparse pattern in attention operations. Our sparsification approach
reduces the computational complexity and memory footprint of the Transformer
during training. Efficient implementations of the layer-wise sparsified
attention algorithm on GPUs are developed, demonstrating a new SPION that
achieves up to 3.08X speedup over existing state-of-the-art sparse Transformer
models, with better evaluation quality.