OSTQuant

Official code for ICLR2025 paper OSTQuant: Refining Large Language Model Quantization with Orthogonal and Scaling Transformations for Better Distribution Fitting

Motivation

Fig1 : Transformation of a batch of data $X \sim \mathcal{N}({\mu}, {\Sigma})$ using different methods. Eigenvalues $\lambda_1$ and $\lambda_2$ represent the spread of the distribution along principal axes after eigenvalue decomposition of $\Sigma$ . (a) shows the original distribution, while (b), (c), and (d) illustrate the effects of the Smooth-based, Rotate-base, and ours OST-based methods, respectively, on QSUR.

OSTQuant Diagram

Fig2 : The overall flow diagram of OSTQuant. The top section of the figure illustrates how the global orthogonal transformation, $R_{res}$, along with the two scaling transformations, $S_{attn}$ and $S_{ffn}$, collaborate within each block to adjust the distributions across the entire network while maintaining computational invariance. The bottom section highlights four equivalent transformation pairs applied to the FFN and Self-Attention layers. Each fully-connected (FC) layer’s activation and weight are influenced by one or more of these transformation pairs. During runtime, these transformation pairs are fused with the weights, ensuring minimal runtime overhead.

Main Results

Table：Comparison of perplexity on WikiText2 and averaged accuracy on nine Zero-Shot tasks. Results for SmoothQuant, GPTQ, OmniQuant, AWQ, and QuaRot are based on official code and SpinQuant's results for LLaMA-2/3 using official weights, with LLaMA-1 from the official code.

#Bits W-A-KV	Method	LLaMA-3 8B		LLaMA-2 7B		LLaMA-2 13B		LLaMA 7B		LLaMA 13B		LLaMA 30B
		0-shot9	Wiki	0-shot9	Wiki	0-shot9	Wiki	0-shot9	Wiki	0-shot9	Wiki	0-shot9	Wiki
		Avg.(↑)	(↓)	Avg.(↑)	(↓)	Avg.(↑)	(↓)	Avg.(↑)	(↓)	Avg.(↑)	(↓)	Avg.(↑)	(↓)
16-16-16	FloatingPoint	68.09	6.14	65.21	5.47	67.61	4.88	64.48	5.68	66.67	5.09	70.00	4.10
4-16-16	RTN	63.70	8.13	61.27	7.02	60.24	6.39	62.67	7.94	63.45	8.60	65.69	6.13
	SmoothQuant	62.79	8.12	58.88	8.03	62.03	5.86	62.24	7.46	62.69	18.75	65.69	5.80
	GPTQ	61.03	7.43	60.86	9.84	64.71	5.79	60.15	7.93	64.36	6.58	66.95	5.26
	OmniQuant	65.66	7.19	63.19	5.74	66.38	5.02	63.42	5.86	66.22	5.21	69.07	4.25
	AWQ	67.03	7.36	63.89	5.83	66.25	5.07	63.30	5.97	65.58	5.28	69.44	4.28
	QuaRot	67.27	6.53	64.30	5.62	66.95	5.00	63.40	5.83	65.91	5.20	69.73	4.27
	SpinQuant	66.54	6.49	63.59	5.58	67.14	5.00	63.94	5.76	66.32	5.16	69.62	4.21
	OSTQuant	67.80	6.53	64.37	5.64	67.31	4.94	64.13	5.81	66.62	5.21	69.84	4.19
4-4-16	RTN	33.42	6e2	32.44	nan	30.86	8e3	32.51	7e3	31.63	3e4	31.57	2e3
	SmoothQuant	33.04	1e3	32.13	nan	34.26	1e3	34.42	3e2	33.29	6e2	34.64	1e3
	GPTQ	32.98	5e2	32.72	nan	30.11	4e3	32.12	1e3	31.51	3e3	30.88	2e3
	QuaRot	61.69	8.02	61.87	6.05	65.13	5.35	61.76	6.22	64.46	5.50	68.14	4.57
	SpinQuant	64.11	7.28	57.37	6.78	63.23	5.24	61.82	6.08	64.59	5.36	68.08	4.53
	OSTQuant	65.14	7.24	63.90	5.60	66.24	5.14	62.72	6.04	65.80	5.40	68.52	4.43
4-4-4	RTN	33.18	7e2	32.67	nan	30.93	7e3	32.87	1e4	31.33	3e4	31.64	2e3
	SmoothQuant	32.96	1e3	32.12	nan	33.36	1e3	33.32	3e2	33.28	5e2	34.65	1e3
	GPTQ	33.71	6e2	33.52	nan	27.85	5e3	31.80	2e3	30.63	3e3	31.07	2e3
	OmniQuant	32.33	4e2	48.40	14.26	50.35	12.30	48.46	11.26	45.63	10.87	45.04	12.35
	QuaRot	61.38	8.18	61.48	6.11	65.16	5.39	61.22	6.26	64.59	5.53	68.08	4.60
	SpinQuant	64.10	7.35	62.01	5.96	64.13	5.74	61.32	6.12	64.95	5.39	68.14	4.55
	OSTQuant	65.37	7.29	63.18	5.91	65.41	5.25	62.55	6.07	65.43	5.40	68.20	4.42

Optimize and Evaluate

You can repdoduce our results with the following command:

export CUDA_VISIBLE_DEVICES="0,1,2,3"
sh scripts/w4a16kv16.sh

Optimized Weights

Due to concerns that personal links could compromise anonymity, the officially optimized orthogonal and smoothing parameters were quickly released once the repository's anonymity was lifted.

Contributing

We welcome contributions from the research and development community! Whether you're interested in improving the existing features, adding new functionalities, or reporting issues, your input is invaluable.

Future Work

We plan to extend OSTQuant to FullyQuant, aiming to quantize all activations within a Transformer block. The Fig3 below demonstrates our design to improve the QSUR of activations across all layers.

OSTQuant for FullyQuant.

Citation

If you find OSTQuant useful in your research, please consider citing our paper:

@inproceedings{hu2025ostquant,
title={{OSTQ}uant: Refining Large Language Model Quantization with Orthogonal and Scaling Transformations for Better Distribution Fitting},
author={Xing Hu, Yuan Cheng, Dawei Yang, Zhixuan Chen, Zukang Xu, Jiangyong Yu, Chen Xu, Zhihang Yuan, Zhe jiang and Sifan Zhou},
booktitle={The Thirteenth International Conference on Learning Representations},
year={2025},
url={https://openreview.net/forum?id=rAcgDBdKnP}
}

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