SFMP: Fine-Grained, Hardware-Friendly and Solver-Free Mixed-Precision Quantization for Large Language Models

Xin Nie, Haicheng Zhang, Liang Dong, Beining Feng, Jinhong Weng, Guiling Sun


Abstract
Mixed-precision quantization is a promising approach for compressing large language models under tight memory budgets. However, existing mixed-precision methods typically suffer from one of two limitations: they either rely on expensive discrete optimization to determine precision allocation, or introduce hardware inefficiencies due to irregular memory layouts. We propose SFMP, a solver-free and hardware-friendly mixed-precision quantization framework for large language models. SFMP defines a theoretically simple objective for mixed-precision quantization and is built upon three novel ideas: 1) Block-wise mixed-precision, enabling fine-grained precision within weight matrices while remaining hardware-friendly; 2) Row-column weight reordering, which improves structural alignment via row and column reordering, incurring only a small activation reordering overhead during inference; 3) Unified GEMM kernel, which supports block-wise mixed-precision GEMM at arbitrary average bit-widths. Extensive experiments demonstrate that SFMP outperforms state-of-the-art layer-wise mixed-precision methods under the same memory constraints, while significantly reducing quantization cost and improving inference efficiency. Code is available at https://github.com/Nkniexin/SFMP.
Anthology ID:
2026.findings-aacl.113
Volume:
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
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Pages:
2233–2259
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URL:
https://aclanthology.org/2026.findings-aacl.113/
DOI:
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Cite (ACL):
Xin Nie, Haicheng Zhang, Liang Dong, Beining Feng, Jinhong Weng, and Guiling Sun. 2026. SFMP: Fine-Grained, Hardware-Friendly and Solver-Free Mixed-Precision Quantization for Large Language Models. In Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026, pages 2233–2259, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
SFMP: Fine-Grained, Hardware-Friendly and Solver-Free Mixed-Precision Quantization for Large Language Models (Nie et al., Findings 2026)
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https://aclanthology.org/2026.findings-aacl.113.pdf