EL-Attention: Memory Efficient Lossless Attention for Generation

Yu Yan · Jiusheng Chen · Weizhen Qi · Nikhil Bhendawade · Yeyun Gong · Nan Duan · Ruofei Zhang

[ Abstract ] [ Livestream: Visit Applications (CV and NLP) ] [ Paper ]
[ Paper ]

Transformer model with multi-head attention requires caching intermediate results for efficient inference in generation tasks. However, cache brings new memory-related costs and prevents leveraging larger batch size for faster speed. We propose memory-efficient lossless attention (called EL-attention) to address this issue. It avoids heavy operations for building multi-head keys and values, cache for them is not needed. EL-attention constructs an ensemble of attention results by expanding query while keeping key and value shared. It produces the same result as multi-head attention with less GPU memory and faster inference speed. We conduct extensive experiments on Transformer, BART, and GPT-2 for summarization and question generation tasks. The results show EL-attention speeds up existing models by 1.6x to 5.3x without accuracy loss.

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