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Hauptverfasser: Wang, Fei, Shen, Li, Ding, Liang, Xue, Chao, Liu, Ye, Ding, Changxing
Format: Preprint
Veröffentlicht: 2025
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Online-Zugang:https://arxiv.org/abs/2510.15304
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author Wang, Fei
Shen, Li
Ding, Liang
Xue, Chao
Liu, Ye
Ding, Changxing
author_facet Wang, Fei
Shen, Li
Ding, Liang
Xue, Chao
Liu, Ye
Ding, Changxing
contents Large Language Models excel at natural language processing tasks, but their massive size leads to high computational and storage demands. Recent works have sought to reduce their model size through layer-wise structured pruning. However, they tend to ignore retaining the capabilities in the pruned part. In this work, we re-examine structured pruning paradigms and uncover several key limitations: 1) notable performance degradation due to direct layer removal, 2) incompetent linear weight layer aggregation, and 3) the lack of effective post-training recovery mechanisms. To address these limitations, we propose CoMe, including a progressive layer pruning framework with a Concatenation-based Merging technology and a hierarchical distillation post-training process. Specifically, we introduce a channel sensitivity metric that utilizes activation intensity and weight norms for fine-grained channel selection. Subsequently, we employ a concatenation-based layer merging method to fuse the most critical channels across adjacent layers, enabling progressive model size reduction. Finally, we propose a hierarchical distillation protocol that leverages the correspondences between the original and pruned model layers established during pruning, thereby enabling efficient knowledge transfer. Experiments on seven benchmarks show that CoMe achieves state-of-the-art performance; when pruning 30% of LLaMA-2-7b's parameters, the pruned model retains 83% of its original average accuracy. Our code is available at https://github.com/MPI-Lab/CoMe.
format Preprint
id arxiv_https___arxiv_org_abs_2510_15304
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Layer as Puzzle Pieces: Compressing Large Language Models through Layer Concatenation
Wang, Fei
Shen, Li
Ding, Liang
Xue, Chao
Liu, Ye
Ding, Changxing
Computer Vision and Pattern Recognition
Machine Learning
Large Language Models excel at natural language processing tasks, but their massive size leads to high computational and storage demands. Recent works have sought to reduce their model size through layer-wise structured pruning. However, they tend to ignore retaining the capabilities in the pruned part. In this work, we re-examine structured pruning paradigms and uncover several key limitations: 1) notable performance degradation due to direct layer removal, 2) incompetent linear weight layer aggregation, and 3) the lack of effective post-training recovery mechanisms. To address these limitations, we propose CoMe, including a progressive layer pruning framework with a Concatenation-based Merging technology and a hierarchical distillation post-training process. Specifically, we introduce a channel sensitivity metric that utilizes activation intensity and weight norms for fine-grained channel selection. Subsequently, we employ a concatenation-based layer merging method to fuse the most critical channels across adjacent layers, enabling progressive model size reduction. Finally, we propose a hierarchical distillation protocol that leverages the correspondences between the original and pruned model layers established during pruning, thereby enabling efficient knowledge transfer. Experiments on seven benchmarks show that CoMe achieves state-of-the-art performance; when pruning 30% of LLaMA-2-7b's parameters, the pruned model retains 83% of its original average accuracy. Our code is available at https://github.com/MPI-Lab/CoMe.
title Layer as Puzzle Pieces: Compressing Large Language Models through Layer Concatenation
topic Computer Vision and Pattern Recognition
Machine Learning
url https://arxiv.org/abs/2510.15304