Radial Attention: $O(n\log n)$ Sparse Attention with Energy Decay for Long Video Generation

Fuente: arXiv
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Main Authors: Li, Xingyang, Li, Muyang, Cai, Tianle, Xi, Haocheng, Yang, Shuo, Lin, Yujun, Zhang, Lvmin, Yang, Songlin, Hu, Jinbo, Peng, Kelly, Agrawala, Maneesh, Stoica, Ion, Keutzer, Kurt, Han, Song
Format: Preprint
Published: 2025
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author Li, Xingyang
Li, Muyang
Cai, Tianle
Xi, Haocheng
Yang, Shuo
Lin, Yujun
Zhang, Lvmin
Yang, Songlin
Hu, Jinbo
Peng, Kelly
Agrawala, Maneesh
Stoica, Ion
Keutzer, Kurt
Han, Song
author_facet Li, Xingyang
Li, Muyang
Cai, Tianle
Xi, Haocheng
Yang, Shuo
Lin, Yujun
Zhang, Lvmin
Yang, Songlin
Hu, Jinbo
Peng, Kelly
Agrawala, Maneesh
Stoica, Ion
Keutzer, Kurt
Han, Song
contents Recent advances in diffusion models have enabled high-quality video generation, but the additional temporal dimension significantly increases computational costs, making training and inference on long videos prohibitively expensive. In this paper, we identify a phenomenon we term Spatiotemporal Energy Decay in video diffusion models: post-softmax attention scores diminish as spatial and temporal distance between tokens increase, akin to the physical decay of signal or waves over space and time in nature. Motivated by this, we propose Radial Attention, a scalable sparse attention mechanism with $\mathcal{O}(n \log n)$ complexity that translates energy decay into exponentially decaying compute density, which is significantly more efficient than standard $\mathcal{O}(n^2)$ dense attention and more expressive than linear attention. Specifically, Radial Attention employs a simple, static attention mask where each token attends to spatially nearby tokens, with the attention window size shrinking with temporal distance. Moreover, it allows pre-trained video diffusion models to extend their generation length with efficient LoRA-based fine-tuning. Extensive experiments show that Radial Attention maintains video quality across Wan2.1-14B, HunyuanVideo, and Mochi 1, achieving up to a 1.9$\times$ speedup over the original dense attention. With minimal tuning, it enables video generation up to 4$\times$ longer while reducing training costs by up to 4.4$\times$ compared to direct fine-tuning and accelerating inference by up to 3.7$\times$ compared to dense attention inference. Code is released at \href{https://github.com/mit-han-lab/radial-attention}{https://github.com/mit-han-lab/radial-attention}.
format Preprint
id arxiv_https___arxiv_org_abs_2506_19852
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Radial Attention: $O(n\log n)$ Sparse Attention with Energy Decay for Long Video Generation
Li, Xingyang
Li, Muyang
Cai, Tianle
Xi, Haocheng
Yang, Shuo
Lin, Yujun
Zhang, Lvmin
Yang, Songlin
Hu, Jinbo
Peng, Kelly
Agrawala, Maneesh
Stoica, Ion
Keutzer, Kurt
Han, Song
Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
Recent advances in diffusion models have enabled high-quality video generation, but the additional temporal dimension significantly increases computational costs, making training and inference on long videos prohibitively expensive. In this paper, we identify a phenomenon we term Spatiotemporal Energy Decay in video diffusion models: post-softmax attention scores diminish as spatial and temporal distance between tokens increase, akin to the physical decay of signal or waves over space and time in nature. Motivated by this, we propose Radial Attention, a scalable sparse attention mechanism with $\mathcal{O}(n \log n)$ complexity that translates energy decay into exponentially decaying compute density, which is significantly more efficient than standard $\mathcal{O}(n^2)$ dense attention and more expressive than linear attention. Specifically, Radial Attention employs a simple, static attention mask where each token attends to spatially nearby tokens, with the attention window size shrinking with temporal distance. Moreover, it allows pre-trained video diffusion models to extend their generation length with efficient LoRA-based fine-tuning. Extensive experiments show that Radial Attention maintains video quality across Wan2.1-14B, HunyuanVideo, and Mochi 1, achieving up to a 1.9$\times$ speedup over the original dense attention. With minimal tuning, it enables video generation up to 4$\times$ longer while reducing training costs by up to 4.4$\times$ compared to direct fine-tuning and accelerating inference by up to 3.7$\times$ compared to dense attention inference. Code is released at \href{https://github.com/mit-han-lab/radial-attention}{https://github.com/mit-han-lab/radial-attention}.
title Radial Attention: $O(n\log n)$ Sparse Attention with Energy Decay for Long Video Generation
topic Computer Vision and Pattern Recognition
Artificial Intelligence
Machine Learning
url https://arxiv.org/abs/2506.19852