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Main Authors: Lin, Zhihang, Lin, Mingbao, Xie, Yuan, Ji, Rongrong
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2503.22342
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author Lin, Zhihang
Lin, Mingbao
Xie, Yuan
Ji, Rongrong
author_facet Lin, Zhihang
Lin, Mingbao
Xie, Yuan
Ji, Rongrong
contents This paper introduces Completion Pruning Policy Optimization (CPPO) to accelerate the training of reasoning models based on Group Relative Policy Optimization (GRPO). GRPO, while effective, incurs high training costs due to the need to sample multiple completions for each question. Our experiment and theoretical analysis reveal that the number of completions impacts model accuracy yet increases training time multiplicatively, and not all completions contribute equally to policy training -- their contribution depends on their relative advantage. To address these issues, we propose CPPO, which prunes completions with low absolute advantages, significantly reducing the number needed for gradient calculation and updates. Additionally, we introduce a dynamic completion allocation strategy to maximize GPU utilization by incorporating additional questions, further enhancing training efficiency. Experiments show that CPPO achieves up to $7.98\times$ speedup on GSM8K and $3.48\times$ on Math while preserving or even enhancing the accuracy compared to the original GRPO. We release our code at \href{https://github.com/lzhxmu/CPPO}{https://github.com/lzhxmu/CPPO}.
format Preprint
id arxiv_https___arxiv_org_abs_2503_22342
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle CPPO: Accelerating the Training of Group Relative Policy Optimization-Based Reasoning Models
Lin, Zhihang
Lin, Mingbao
Xie, Yuan
Ji, Rongrong
Artificial Intelligence
This paper introduces Completion Pruning Policy Optimization (CPPO) to accelerate the training of reasoning models based on Group Relative Policy Optimization (GRPO). GRPO, while effective, incurs high training costs due to the need to sample multiple completions for each question. Our experiment and theoretical analysis reveal that the number of completions impacts model accuracy yet increases training time multiplicatively, and not all completions contribute equally to policy training -- their contribution depends on their relative advantage. To address these issues, we propose CPPO, which prunes completions with low absolute advantages, significantly reducing the number needed for gradient calculation and updates. Additionally, we introduce a dynamic completion allocation strategy to maximize GPU utilization by incorporating additional questions, further enhancing training efficiency. Experiments show that CPPO achieves up to $7.98\times$ speedup on GSM8K and $3.48\times$ on Math while preserving or even enhancing the accuracy compared to the original GRPO. We release our code at \href{https://github.com/lzhxmu/CPPO}{https://github.com/lzhxmu/CPPO}.
title CPPO: Accelerating the Training of Group Relative Policy Optimization-Based Reasoning Models
topic Artificial Intelligence
url https://arxiv.org/abs/2503.22342