斯坦福：优化器「诸神之战」？AdamW 凭「稳定」胜出

Core Insights - The article discusses the dominance of Adam and its improved version AdamW in the pre-training of open-weight language models since 2014, emphasizing their stability and rapid convergence under large datasets [1] - It highlights the significance of optimizer design in relation to convergence speed and computational costs as model sizes increase, with matrix-based optimizers showing a 30-40% iteration-level acceleration compared to well-tuned AdamW [1][15] - The research identifies two methodological flaws that may lead to underestimating the performance of baseline optimizers like AdamW: unfair hyperparameter tuning and insufficient testing scale [3][7] Summary by Sections Optimizer Performance - Matrix-based optimizers (e.g., Muon, Soap, Kron) outperform scalar-based optimizers (e.g., AdamW, Nesterov AdamW, Mars) in terms of consistent acceleration across various data-model ratios [9][15] - The performance of optimizers tends to diminish as model size increases, with some optimizers showing only a 1.1x acceleration at 12 billion parameters compared to AdamW [9][25] Hyperparameter Tuning - Proper hyperparameter tuning is crucial, as even a single parameter adjustment (like learning rate) can lead to significant performance improvements, such as a 2x speedup on a model with 130 million parameters [6][18] - Fixed shared hyperparameters do not ensure fair comparisons between different optimizers, as preferences for values like weight decay can vary significantly [4][15] Testing Methodology - The research emphasizes the need for rigorous independent tuning of hyperparameters for each optimizer to ensure fair comparisons, as blindly transferring hyperparameters can lead to misleading results [15][18] - Short-term evaluations can be misleading, as performance rankings may reverse during training due to learning rate decay [15][20] Case Studies and Findings - The study includes case studies on larger models, confirming that the predicted optimal configurations align closely with actual performance, validating the effectiveness of their scaling laws [23] - In extreme data-to-model ratios (e.g., 16x Chinchilla), optimizers like Soap and Kron demonstrate superior performance over Muon, indicating their effectiveness in high data scenarios [26]