PPL-Factory: Task-Aware and Budget-Aware Data Selection from Language Modeling to Reasoning

Hang Zhang, Warren J. Gross


Abstract
Not all training samples contribute equally to the large language model fine-tuning. Selecting informative training samples can reduce the computational cost while preserving downstream performance. Many existing data selection methods rely on indirect heuristics, such as data quality, diversity or reasoning trace length. However, the effectiveness of these fixed criteria is task-dependent and difficult to generalize across diverse downstream tasks. Perplexity-based data selection provides a simple and model-aware solution to estimate the sample difficulty, but existing approaches typically score the entire training sequence and ignore the difference in learning objectives of language modeling and reasoning tasks. In this paper, we propose **PPL-Factory**, a simple and interpretable data selection framework that combines task-aware perplexity-based scores and data budget-aware selection criteria. Experiments on GSM8K demonstrate that PPL-Factory outperforms other state-of-the-art data selection methods using only 1% of the training set. With 10% of the data, PPL-Factory exceeds full-data fine-tuning accuracy by 0.9 on GSM8K and 4.8 on MATH. Overall, our results demonstrate that task-aware and budget-aware perplexity-based selection provides an effective and applicable approach for efficient fine-tuning.
Anthology ID:
2026.findings-aacl.202
Volume:
Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026
Month:
November
Year:
2026
Address:
Hengqin, China
Editors:
Yue Zhang, Ruifeng Xu, Ayu Purwarianti, Tong Rong, Jun Suzuki
Venue:
Findings
SIG:
Publisher:
Association for Computational Linguistics
Note:
Pages:
4025–4038
Language:
URL:
https://aclanthology.org/2026.findings-aacl.202/
DOI:
Bibkey:
Cite (ACL):
Hang Zhang and Warren J. Gross. 2026. PPL-Factory: Task-Aware and Budget-Aware Data Selection from Language Modeling to Reasoning. In Findings of the Association for Computational Linguistics: IJCNLP-AACL 2026, pages 4025–4038, Hengqin, China. Association for Computational Linguistics.
Cite (Informal):
PPL-Factory: Task-Aware and Budget-Aware Data Selection from Language Modeling to Reasoning (Zhang & Gross, Findings 2026)
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PDF:
https://aclanthology.org/2026.findings-aacl.202.pdf