Rethinking Layer Redundancy: Calibration Matters More Than Search in LLM Depth Pruning

Fuente: arXiv
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Autori principali: Kim, Minkyu, Yun, Vincent-Daniel, Kim, Youngrae, Cho, Suin, Lim, Woosang, Lee, Sunwoo
Natura: Preprint
Pubblicazione: 2026
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author Kim, Minkyu
Yun, Vincent-Daniel
Kim, Youngrae
Cho, Suin
Lim, Woosang
Lee, Sunwoo
author_facet Kim, Minkyu
Yun, Vincent-Daniel
Kim, Youngrae
Cho, Suin
Lim, Woosang
Lee, Sunwoo
contents Depth pruning improves the inference efficiency of large language models by removing Transformer blocks. Prior work typically treats layer redundancy as an inherent structural property of pretrained networks, emphasizing importance criteria and search algorithms to identify removable layers. In this study, we empirically investigate depth pruning from a functional perspective. Evaluating representative LLM families across diverse calibration configurations and multiple search algorithms, we show that different configurations produce different pruning patterns. Furthermore, under a fixed calibration configuration, complex search algorithms yield marginal performance improvements over simple one-shot methods, converging to similar pruned subsets. Overall, our results suggest that the calibration configuration plays a substantially larger role than the choice of search algorithm in shaping pruning patterns and calibration perplexity, while contributing comparably to variance in downstream reasoning accuracy. This indicates that future pruning efforts may benefit from prioritizing the calibration configuration over search complexity.
format Preprint
id arxiv_https___arxiv_org_abs_2604_24938
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Rethinking Layer Redundancy: Calibration Matters More Than Search in LLM Depth Pruning
Kim, Minkyu
Yun, Vincent-Daniel
Kim, Youngrae
Cho, Suin
Lim, Woosang
Lee, Sunwoo
Machine Learning
Artificial Intelligence
Computation and Language
Depth pruning improves the inference efficiency of large language models by removing Transformer blocks. Prior work typically treats layer redundancy as an inherent structural property of pretrained networks, emphasizing importance criteria and search algorithms to identify removable layers. In this study, we empirically investigate depth pruning from a functional perspective. Evaluating representative LLM families across diverse calibration configurations and multiple search algorithms, we show that different configurations produce different pruning patterns. Furthermore, under a fixed calibration configuration, complex search algorithms yield marginal performance improvements over simple one-shot methods, converging to similar pruned subsets. Overall, our results suggest that the calibration configuration plays a substantially larger role than the choice of search algorithm in shaping pruning patterns and calibration perplexity, while contributing comparably to variance in downstream reasoning accuracy. This indicates that future pruning efforts may benefit from prioritizing the calibration configuration over search complexity.
title Rethinking Layer Redundancy: Calibration Matters More Than Search in LLM Depth Pruning
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2604.24938