arXiv Machine Learning

ClusterAttention: A training-free speedup of bidirectional attention

ClusterAttention is a training‑free technique that speeds up bidirectional attention by recursively clustering keys and queries into fixed‑size, power‑of‑two blocks, enabling block‑sparse attention to match dense attention latency on GPUs. The method derives error bounds for sparse attention, showing tighter clusters can reduce error when compensated via centroids, and demonstrates significant speedups—up to six‑fold on large tabular data and 1.8× on video generation—while preserving over 99% of dense accuracy.

Hugging Face Trending Papers
Aug 13

SCOPE: Subspace Clustering with Online Per-Head Top-K Estimation for Sparse Video Attention

Diffusion Transformers (DiTs) incur quadratic self-attention cost over spatiotemporal tokens. Existing training-free sparse attention methods often construct sparse masks from block-level or cluster-level proxy scores, which can obscure fine-grained differences among keys and miss high contribution keys under aggressive sparsity.

arXiv AI
Aug 20

Partition the Support, Reconstruct the Residual: Training-Free Sparse Attention for Video Generation and World Models

The paper introduces SparsePR, a training‑free block‑sparse attention method for video transformers that partitions query‑key responses and reconstructs the residual via probe‑fitted affine corrections. By pairing sampled‑query key responses into K/V groups and using centroids to guide shared routing, SparsePR reduces attention‑reconstruction error across diverse video generation and world‑model tasks. Experiments show consistent error reductions, with probe fitting contributing most of the improvement, while maintaining generation quality at 22.0–26.0% executed‑pair density and delivering 1.48×–2.61× speedups.

By Pardis Taghavi, Reza Langari, Gaurav Pandey
arXiv Machine Learning
2d ago

Benchmarking Attention for Tabular Foundation Models

The paper introduces a reproducible benchmark for evaluating attention mechanisms in tabular foundation models, focusing on the distinct row and column attention patterns that differ from language model attention. It compares several backends—Torch SDPA, FlashAttention variants, vLLM, and SageAttention—across realistic tabular shapes on A100, H100, and B200 GPUs, revealing that optimal backend choice varies by attention type, hardware, and model specifics. The study finds FlashAttention generally performs best, but CuDNN can outperform it for column attention on longer sequences, while SageAttention excels for large row sequences beyond 16k rows.

By Maximilian Schambach, Clemens Biehl, Sam Thelin
arXiv AI
Sep 21

RBS-Attention: Radius-Bounded Sparse Prefill for Long-Context Large Language Models

RBS-Attention introduces a training‑free, radius‑bounded sparse prefill strategy for long‑context large language models, addressing the mean dilution problem where a block centroid can miss highly relevant tokens. The method employs two complementary selection branches: a centroid base branch that captures average relevance and a rescue branch that uses the maximum key‑block radius to flag under‑estimated blocks. Experiments on Qwen3 models demonstrate significant speedups—over 20× in standalone prefill‑attention and nearly 6× in end‑to‑first‑token time—while maintaining competitive accuracy compared to dense attention.

By Chuxu Song, Jiuqi Wei, Zhencan Peng
arXiv AI
Jun 12

MiniMax Sparse Attention

arXiv:2606. 13392v1 Announce Type: new Abstract: Ultra-long-context capability is becoming indispensable for frontier LLMs: agentic workflows, repository-scale code reasoning, and persistent memory all require the model to jointly attend over hundreds of thousands to millions of tokens, yet the quadratic cost of softmax attention makes this untenable at deployment scale.

By Xunhao Lai, Weiqi Xu, Yufeng Yang, Qiaorui Chen, Yang Xu, Lunbin Zeng, Xiaolong Li, Haohai Sun, Haichao Zhu, Vito Zhang, Pengyu Zhao