D-QRELO: Training- and Data-Free Delta Compression for Large Language Models via Quantization and Residual Low-Rank Approximation

Fuente: arXiv
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Autores principales: Li, Junlin, Song, Shuangyong, Du, Guodong, Wong, Ngai, Liu, Xuebo, Li, Yongxiang, Zhang, Min, Li, Jing, Li, Xuelong
Formato: Preprint
Publicado: 2026
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author Li, Junlin
Song, Shuangyong
Du, Guodong
Wong, Ngai
Liu, Xuebo
Li, Yongxiang
Zhang, Min
Li, Jing
Li, Xuelong
author_facet Li, Junlin
Song, Shuangyong
Du, Guodong
Wong, Ngai
Liu, Xuebo
Li, Yongxiang
Zhang, Min
Li, Jing
Li, Xuelong
contents Supervised Fine-Tuning (SFT) accelerates taskspecific large language models (LLMs) development, but the resulting proliferation of finetuned models incurs substantial memory overhead. Delta compression addresses this by retaining a single pre-trained LLM with multiple compressed delta weights. However, existing methods fail on models fine-tuned with largescale datasets. We find that larger SFT data scale amplifies delta parameter magnitude, singular values, and entropy, exacerbating compression errors. To tackle this, we propose DQRELO (Delta Compression via Quantization and Residual Low-Rank), a novel training- and data-free delta compression method. It combines coarse-grained one-bit quantization to capture the dominant structure of the delta, followed by compensated residual low-rank approximation to recover fine-grained details from the smaller residual error. Experiments on various LLMs spanning dense and MoE architectures across multiple domains under this challenging setting demonstrate that DQRELO outperforms existing methods. Moreover, we establish key design principles for delta compression through extensive empirical analysis, demonstrating how task difficulty, architecture, and layer positioning create predictable patterns that can guide optimal compression strategies in production systems.
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institution arXiv
publishDate 2026
record_format arxiv
spellingShingle D-QRELO: Training- and Data-Free Delta Compression for Large Language Models via Quantization and Residual Low-Rank Approximation
Li, Junlin
Song, Shuangyong
Du, Guodong
Wong, Ngai
Liu, Xuebo
Li, Yongxiang
Zhang, Min
Li, Jing
Li, Xuelong
Machine Learning
Artificial Intelligence
Supervised Fine-Tuning (SFT) accelerates taskspecific large language models (LLMs) development, but the resulting proliferation of finetuned models incurs substantial memory overhead. Delta compression addresses this by retaining a single pre-trained LLM with multiple compressed delta weights. However, existing methods fail on models fine-tuned with largescale datasets. We find that larger SFT data scale amplifies delta parameter magnitude, singular values, and entropy, exacerbating compression errors. To tackle this, we propose DQRELO (Delta Compression via Quantization and Residual Low-Rank), a novel training- and data-free delta compression method. It combines coarse-grained one-bit quantization to capture the dominant structure of the delta, followed by compensated residual low-rank approximation to recover fine-grained details from the smaller residual error. Experiments on various LLMs spanning dense and MoE architectures across multiple domains under this challenging setting demonstrate that DQRELO outperforms existing methods. Moreover, we establish key design principles for delta compression through extensive empirical analysis, demonstrating how task difficulty, architecture, and layer positioning create predictable patterns that can guide optimal compression strategies in production systems.
title D-QRELO: Training- and Data-Free Delta Compression for Large Language Models via Quantization and Residual Low-Rank Approximation
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2604.16940