Token Cleaning: Fine-Grained Data Selection for LLM Supervised Fine-Tuning

Fuente: arXiv
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Hauptverfasser: Pang, Jinlong, Di, Na, Zhu, Zhaowei, Wei, Jiaheng, Cheng, Hao, Qian, Chen, Liu, Yang
Format: Preprint
Veröffentlicht: 2025
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author Pang, Jinlong
Di, Na
Zhu, Zhaowei
Wei, Jiaheng
Cheng, Hao
Qian, Chen
Liu, Yang
author_facet Pang, Jinlong
Di, Na
Zhu, Zhaowei
Wei, Jiaheng
Cheng, Hao
Qian, Chen
Liu, Yang
contents Recent studies show that in supervised fine-tuning (SFT) of large language models (LLMs), data quality matters more than quantity. While most data cleaning methods concentrate on filtering entire samples, the quality of individual tokens within a sample can vary significantly. After pre-training, even in high-quality samples, patterns or phrases that are not task-related can be redundant, uninformative, or even harmful. Continuing to fine-tune on these patterns may offer limited benefit and even degrade downstream task performance. In this paper, we investigate token quality from a noisy-label perspective and propose a generic token cleaning pipeline for SFT tasks. Our method filters out uninformative tokens while preserving those carrying key task-specific information. Specifically, we first evaluate token quality by examining the influence of model updates on each token, then apply a threshold-based separation. The token influence can be measured in a single pass with a fixed reference model or iteratively with self-evolving reference models. The benefits and limitations of both methods are analyzed theoretically by error upper bounds. Extensive experiments show that our framework consistently improves downstream performance. Code is available at https://github.com/UCSC-REAL/TokenCleaning.
format Preprint
id arxiv_https___arxiv_org_abs_2502_01968
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Token Cleaning: Fine-Grained Data Selection for LLM Supervised Fine-Tuning
Pang, Jinlong
Di, Na
Zhu, Zhaowei
Wei, Jiaheng
Cheng, Hao
Qian, Chen
Liu, Yang
Computation and Language
Artificial Intelligence
Recent studies show that in supervised fine-tuning (SFT) of large language models (LLMs), data quality matters more than quantity. While most data cleaning methods concentrate on filtering entire samples, the quality of individual tokens within a sample can vary significantly. After pre-training, even in high-quality samples, patterns or phrases that are not task-related can be redundant, uninformative, or even harmful. Continuing to fine-tune on these patterns may offer limited benefit and even degrade downstream task performance. In this paper, we investigate token quality from a noisy-label perspective and propose a generic token cleaning pipeline for SFT tasks. Our method filters out uninformative tokens while preserving those carrying key task-specific information. Specifically, we first evaluate token quality by examining the influence of model updates on each token, then apply a threshold-based separation. The token influence can be measured in a single pass with a fixed reference model or iteratively with self-evolving reference models. The benefits and limitations of both methods are analyzed theoretically by error upper bounds. Extensive experiments show that our framework consistently improves downstream performance. Code is available at https://github.com/UCSC-REAL/TokenCleaning.
title Token Cleaning: Fine-Grained Data Selection for LLM Supervised Fine-Tuning
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2502.01968