Designing Spatial Architectures for Sparse Attention: STAR Accelerator via Cross-Stage Tiling

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Auteurs principaux: Wang, Huizheng, Wei, Taiquan, Wang, Hongbin, Wang, Zichuan, Tang, Xinru, Yue, Zhiheng, Wei, Shaojun, Hu, Yang, Yin, Shouyi
Format: Preprint
Publié: 2025
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author Wang, Huizheng
Wei, Taiquan
Wang, Hongbin
Wang, Zichuan
Tang, Xinru
Yue, Zhiheng
Wei, Shaojun
Hu, Yang
Yin, Shouyi
author_facet Wang, Huizheng
Wei, Taiquan
Wang, Hongbin
Wang, Zichuan
Tang, Xinru
Yue, Zhiheng
Wei, Shaojun
Hu, Yang
Yin, Shouyi
contents Large language models (LLMs) rely on self-attention for contextual understanding, demanding high-throughput inference and large-scale token parallelism (LTPP). Existing dynamic sparsity accelerators falter under LTPP scenarios due to stage-isolated optimizations. Revisiting the end-to-end sparsity acceleration flow, we identify an overlooked opportunity: cross-stage coordination can substantially reduce redundant computation and memory access. We propose STAR, a cross-stage compute- and memory-efficient algorithm-hardware co-design tailored for Transformer inference under LTPP. STAR introduces a leading-zero-based sparsity prediction using log-domain add-only operations to minimize prediction overhead. It further employs distributed sorting and a sorted updating FlashAttention mechanism, guided by a coordinated tiling strategy that enables fine-grained stage interaction for improved memory efficiency and latency. These optimizations are supported by a dedicated STAR accelerator architecture, achieving up to 9.2$\times$ speedup and 71.2$\times$ energy efficiency over A100, and surpassing SOTA accelerators by up to 16.1$\times$ energy and 27.1$\times$ area efficiency gains. Further, we deploy STAR onto a multi-core spatial architecture, optimizing dataflow and execution orchestration for ultra-long sequence processing. Architectural evaluation shows that, compared to the baseline design, Spatial-STAR achieves a 20.1$\times$ throughput improvement.
format Preprint
id arxiv_https___arxiv_org_abs_2512_20198
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Designing Spatial Architectures for Sparse Attention: STAR Accelerator via Cross-Stage Tiling
Wang, Huizheng
Wei, Taiquan
Wang, Hongbin
Wang, Zichuan
Tang, Xinru
Yue, Zhiheng
Wei, Shaojun
Hu, Yang
Yin, Shouyi
Hardware Architecture
Signal Processing
Large language models (LLMs) rely on self-attention for contextual understanding, demanding high-throughput inference and large-scale token parallelism (LTPP). Existing dynamic sparsity accelerators falter under LTPP scenarios due to stage-isolated optimizations. Revisiting the end-to-end sparsity acceleration flow, we identify an overlooked opportunity: cross-stage coordination can substantially reduce redundant computation and memory access. We propose STAR, a cross-stage compute- and memory-efficient algorithm-hardware co-design tailored for Transformer inference under LTPP. STAR introduces a leading-zero-based sparsity prediction using log-domain add-only operations to minimize prediction overhead. It further employs distributed sorting and a sorted updating FlashAttention mechanism, guided by a coordinated tiling strategy that enables fine-grained stage interaction for improved memory efficiency and latency. These optimizations are supported by a dedicated STAR accelerator architecture, achieving up to 9.2$\times$ speedup and 71.2$\times$ energy efficiency over A100, and surpassing SOTA accelerators by up to 16.1$\times$ energy and 27.1$\times$ area efficiency gains. Further, we deploy STAR onto a multi-core spatial architecture, optimizing dataflow and execution orchestration for ultra-long sequence processing. Architectural evaluation shows that, compared to the baseline design, Spatial-STAR achieves a 20.1$\times$ throughput improvement.
title Designing Spatial Architectures for Sparse Attention: STAR Accelerator via Cross-Stage Tiling
topic Hardware Architecture
Signal Processing
url https://arxiv.org/abs/2512.20198