Microsoft(US:MSFT) 机器之心·2025-09-01 02:49Core Viewpoint - The article discusses the evolution and significance of the Group Relative Policy Optimization (GRPO) algorithm in the context of large language models and reinforcement learning, highlighting its advantages and limitations compared to previous methods like Proximal Policy Optimization (PPO) [4][38]. Summary by Sections Development of Large Language Models - The rapid advancement of large language models has led to the emergence of various post-training methods, with GRPO being a notable innovation that enhances reinforcement learning paradigms [3][5]. Post-Training and Reinforcement Learning - Post-training is crucial for refining models' capabilities in specific domains, enhancing adaptability and flexibility to meet diverse application needs [12][11]. - Reinforcement learning, particularly through human feedback (RLHF), plays a vital role in the post-training phase, aiming to optimize model outputs based on user preferences [14][19]. GRPO and Its Advantages - GRPO eliminates the need for a separate critic model, reducing memory and computational costs significantly compared to PPO, which requires dual networks [30][35]. - The GRPO framework utilizes historical performance data to establish a baseline for evaluating model improvements, thus simplifying the training process [34][35]. Comparison of GRPO and PPO - GRPO offers substantial improvements in memory requirements and training speed, making it a more efficient choice for large language model training [37]. - Despite its advantages, GRPO still faces stability issues similar to those of PPO, particularly in smaller-scale reinforcement learning tasks [39]. Recent Innovations: DAPO, GSPO, and GFPO - DAPO introduces enhancements to GRPO, such as Clip-Higher and dynamic sampling, to address practical challenges encountered during training [41][42]. - GSPO advances the methodology by shifting the focus from token-level to sequence-level importance sampling, significantly improving training stability [48][49]. - GFPO allows for simultaneous optimization of multiple response attributes, addressing limitations of GRPO related to scalar feedback and multi-round reasoning tasks [61][63]. Conclusion - The evolution of post-training methods, from PPO to GRPO and beyond, illustrates a clear trajectory in optimizing large language models, with GRPO serving as a pivotal point for further advancements in the field [81][82].