Checkpoint Merging via Bayesian Optimization in LLM Pretraining

Checkpoint Merging via Bayesian Optimization in LLM Pretraining

28 Mar 2024 | Deyuan Liu, Zecheng Wang, Bingning Wang, Weipeng Chen, Chunshan Li, Zhiying Tu, Dianhui Chu, Bo Li, Dianbo Sui
The paper "Checkpoint Merging via Bayesian Optimization in LLM Pretraining" addresses the significant computational and environmental costs associated with training large language models (LLMs) such as GPT-4 and Gemini. To mitigate these challenges, the authors propose a method for checkpoint merging during pretraining, which involves averaging parameters from multiple checkpoints to enhance model performance with minimal additional resources. The key contributions of the paper are: 1. **Checkpoint Merging Method**: The authors conduct pilot experiments to explore the characteristics of checkpoint merging and determine the optimal merging weights using Bayesian optimization. This method is designed to find the best or near-optimal merging weights by optimizing an expensive, black-box, derivative-free objective function. 2. **Bayesian Optimization**: The proposed method leverages Bayesian optimization to find the optimal merging weights. This approach is effective for optimizing complex, non-convex functions and is particularly useful in scenarios where direct evaluation is costly or infeasible. 3. **Experimental Results**: The authors demonstrate that their proposed method significantly enhances pretraining performance, offering substantial benefits with minimal additional resources. Additionally, the merged checkpoints exhibit strong generalization capabilities across various domains, indicating that the merging process does not compromise the model's ability to perform on unseen data. 4. **Discussion and Limitations**: The paper discusses the impact of varying the size of the held-out dataset and the merging weight searching space on the effectiveness of the method. It also highlights limitations, such as the lack of transparency in the underlying mechanisms of checkpoint merging and the resource-intensive nature of using Gaussian processes for optimal merging weight search. Overall, the paper provides a novel approach to reducing the computational costs of LLM pretraining while maintaining or improving model performance, making it a valuable contribution to the field of large language model training.The paper "Checkpoint Merging via Bayesian Optimization in LLM Pretraining" addresses the significant computational and environmental costs associated with training large language models (LLMs) such as GPT-4 and Gemini. To mitigate these challenges, the authors propose a method for checkpoint merging during pretraining, which involves averaging parameters from multiple checkpoints to enhance model performance with minimal additional resources. The key contributions of the paper are: 1. **Checkpoint Merging Method**: The authors conduct pilot experiments to explore the characteristics of checkpoint merging and determine the optimal merging weights using Bayesian optimization. This method is designed to find the best or near-optimal merging weights by optimizing an expensive, black-box, derivative-free objective function. 2. **Bayesian Optimization**: The proposed method leverages Bayesian optimization to find the optimal merging weights. This approach is effective for optimizing complex, non-convex functions and is particularly useful in scenarios where direct evaluation is costly or infeasible. 3. **Experimental Results**: The authors demonstrate that their proposed method significantly enhances pretraining performance, offering substantial benefits with minimal additional resources. Additionally, the merged checkpoints exhibit strong generalization capabilities across various domains, indicating that the merging process does not compromise the model's ability to perform on unseen data. 4. **Discussion and Limitations**: The paper discusses the impact of varying the size of the held-out dataset and the merging weight searching space on the effectiveness of the method. It also highlights limitations, such as the lack of transparency in the underlying mechanisms of checkpoint merging and the resource-intensive nature of using Gaussian processes for optimal merging weight search. Overall, the paper provides a novel approach to reducing the computational costs of LLM pretraining while maintaining or improving model performance, making it a valuable contribution to the field of large language model training.
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[slides and audio] Checkpoint Merging via Bayesian Optimization in LLM Pretraining