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Why Lift So Heavy? Slimming Large Language Models by Cutting Off the Layers

MCML Authors

Ercong Nie

→ Group Hinrich Schütze
Computational Linguistics

Bolei Ma

→ Group Frauke Kreuter
Social Data Science and AI

Abstract

Large Language Models (LLMs) demonstrate exceptional language understanding and generation capabilities by learning from context. Leveraging the strong in-context learning (ICL) abilities of LLMs, prompt-based fine-tuning has proven to be effective for enhancing the adaptability and alignment of LLMs, especially in low-data scenarios. However, the billions of parameters resulting from layer stacking in LLMs present significant computational challenges, limiting the practicality of fine-tuning. To tackle this problem, we explore the application of layer-wise model pruning in prompt-based fine-tuning of LLMs for few-shot learning scenarios. Our approach involves dropping certain model layers and fine-tuning the model with the remaining layers. Surprisingly, we observe that even with fewer layers, LLMs maintain similar or better performance levels, particularly in prompt-based fine-tuning for text classification tasks. Remarkably, in certain cases, models with a single layer outperform their fully layered counterparts. These findings offer valuable insights for future work aimed at mitigating the size constraints of LLMs while preserving their performance, thereby opening avenues for significantly more efficient use of LLMs.

inproceedings YNM+25