Rethinking Pruning Large Language Models: Benefits and Pitfalls of Reconstruction Error Minimization

Fuente: arXiv
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Autori principali: Shin, Sungbin, Park, Wonpyo, Lee, Jaeho, Lee, Namhoon
Natura: Preprint
Pubblicazione: 2024
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author Shin, Sungbin
Park, Wonpyo
Lee, Jaeho
Lee, Namhoon
author_facet Shin, Sungbin
Park, Wonpyo
Lee, Jaeho
Lee, Namhoon
contents This work suggests fundamentally rethinking the current practice of pruning large language models (LLMs). The way it is done is by divide and conquer: split the model into submodels, sequentially prune them, and reconstruct predictions of the dense counterparts on small calibration data one at a time; the final model is obtained simply by putting the resulting sparse submodels together. While this approach enables pruning under memory constraints, it generates high reconstruction errors. In this work, we first present an array of reconstruction techniques that can significantly reduce this error by more than $90\%$. Unwittingly, however, we discover that minimizing reconstruction error is not always ideal and can overfit the given calibration data, resulting in rather increased language perplexity and poor performance at downstream tasks. We find out that a strategy of self-generating calibration data can mitigate this trade-off between reconstruction and generalization, suggesting new directions in the presence of both benefits and pitfalls of reconstruction for pruning LLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2406_15524
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Rethinking Pruning Large Language Models: Benefits and Pitfalls of Reconstruction Error Minimization
Shin, Sungbin
Park, Wonpyo
Lee, Jaeho
Lee, Namhoon
Computation and Language
Machine Learning
This work suggests fundamentally rethinking the current practice of pruning large language models (LLMs). The way it is done is by divide and conquer: split the model into submodels, sequentially prune them, and reconstruct predictions of the dense counterparts on small calibration data one at a time; the final model is obtained simply by putting the resulting sparse submodels together. While this approach enables pruning under memory constraints, it generates high reconstruction errors. In this work, we first present an array of reconstruction techniques that can significantly reduce this error by more than $90\%$. Unwittingly, however, we discover that minimizing reconstruction error is not always ideal and can overfit the given calibration data, resulting in rather increased language perplexity and poor performance at downstream tasks. We find out that a strategy of self-generating calibration data can mitigate this trade-off between reconstruction and generalization, suggesting new directions in the presence of both benefits and pitfalls of reconstruction for pruning LLMs.
title Rethinking Pruning Large Language Models: Benefits and Pitfalls of Reconstruction Error Minimization
topic Computation and Language
Machine Learning
url https://arxiv.org/abs/2406.15524