HISA: Efficient Hierarchical Indexing for Fine-Grained Sparse Attention
Quick summary
arXiv:2603.28458v4 Announce Type: replace-cross Abstract: Token-level sparse attention mechanisms, exemplified by DeepSeek Sparse Attention (DSA), achieve fine-grained key selection by scoring every historical key for each query through a lightweight indexer, then computing attention only on the selected subset. While the downstream sparse attention itself scales favorably, the indexer must still scan the entire prefix for every query, introducing an per-layer bottleneck that grows prohibitively with context length. We propose HISA (Hierarchical Indexed Sparse Attention), a plug-and-play repla
Key takeaways
- arXiv:2603.28458v4 Announce Type: replace-cross Abstract: Token-level sparse attention mechanisms, exemplified by DeepSeek Sparse Attention (DSA), achieve fine-grained key selection by scoring every historical key for each query through a lightweight indexer, then computing attention only on the selected subset.
- While the downstream sparse attention itself scales favorably, the indexer must still scan the entire prefix for every query, introducing an per-layer bottleneck that grows prohibitively with context length.
- We propose HISA (Hierarchical Indexed Sparse Attention), a plug-and-play repla
Why it matters
“HISA: Efficient Hierarchical Indexing for Fine-Grained Sparse Attention” should be evaluated beyond branding and benchmark scores. Its practical importance will emerge in task accuracy, latency, unit cost, safety and integration with real workflows.

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