Efficient Attention via Pre-Scoring: Prioritizing Informative Keys in Transformers (2505.11040v1)

Abstract: Recent advances in transformer architectures deeply enhance long-context LLMing. Among them, HyperAttention achieves competitive efficiency by combining a single-level LSH-based clustering with uniform residual sampling. However,such a sampling limits crucial keys' capturing, which in turn raises the overall perplexity. In this paper, we propose a pre-scoring mechanism to assist HyperAttention to prioritize significant keys. Specifically, we introduce three scoring methods: K-means clustering, K-median clustering, and leverage score-based ranking (inspired by LevAttention) to filter keys effectively. We further replace HyperAttention's original uniform residual sampling entirely, relying exclusively on our pre-scoring mechanism. Experiments on ChatGLM2 (131k token context) reduce perplexity from 12 to 8.3, which outperforms standard HyperAttention. Moreover, when running on the Vision-Transformer (ViT), our method shows that it can guarantee similar accuracy compared with LevAttention, and will surpass LevAttention given specific parameters. Although this method introduces computational overhead, its combination with HyperAttention remains 20 times faster than FlashAttention, providing a balanced trade-off between speed and modeling accuracy. Our results highlight the effectiveness of integrating pre-scoring into hierarchical attention mechanisms, significantly improving Transformer's efficiency.