Conda优化器让大模型训练更快更稳,收敛速度提升2-2.5倍。
Conda: Column-Normalized Adam for Training Large Language Models Faster
- 通过列归一化投影梯度,兼顾谱条件改善与坐标自适应性。
- 在LLaMA系列上,收敛速度比AdamW快2至2.5倍,训练时间显著缩短。
- 适合大规模语言模型预训练,对不同训练设置均表现稳健。
大型语言模型(LLMs)展现出强大的泛化能力和涌现特性,但其预训练过程仍计算成本高昂且对优化动态敏感。尽管基于Adam的优化器通过坐标自适应学习率实现快速收敛,但近期研究发现其更新常存在不良的谱条件和低秩结构,影响效率。Muon通过全局谱归一化解决此问题,却牺牲了Adam的坐标自适应性。本文提出列归一化Adam(Conda),将更新投影至正交子空间,并基于投影梯度进行列方向二阶矩归一化,同时实现优异的谱条件和坐标自适应性。该设计缓解了Adam的谱病态问题,又保留其快速收敛特性。在LLaMA和GPT-2系列上的大量实验表明,Conda持续优于AdamW、Muon及其他基线。尤其在LLaMA系列上,其收敛速度达AdamW的2-2.5倍(以训练步数和训练时间计)。进一步消融实验验证了其在多种训练设置下的鲁棒性。结果表明,Conda是大规模LLM训练中有效且通用的优化器。代码已开源于https://github.com/jie040109/Conda。
原文摘要 · Abstract (English)
Large language models (LLMs) have demonstrated impressive generalization and emergent capabilities, yet their pre-training remains computationally expensive and sensitive to optimization dynamics. While Adam-based optimizers offer fast convergence by adapting learning rates coordinate-wise, recent studies reveal that their updates often suffer from poor spectral conditioning and low-rank structures, hindering efficiency. Muon addresses this issue via global spectral normalization but lacks the per-coordinate adaptivity of Adam. In this work, we propose Column-Normalized Adam (Conda), a novel optimizer that bridges the strengths of both approaches. Conda projects updates into an orthogonal subspace and applies column-wise second moment normalization based on the projected gradients, thereby achieving both improved spectral conditioning and maintaining coordinate-wise adaptivity. This design alleviates the spectral pathologies of Adam while preserving its fast convergence behavior. Extensive experiments on the LLaMA and GPT-2 series show that Conda consistently outperforms AdamW, Muon, and other baselines in pre-training. Remarkably, on the LLaMA series, Conda achieves 2-2.5 the convergence speed of AdamW, measured in both training steps and training time. Further ablations demonstrate its robustness under diverse training setups. These results collectively highlight Conda as an effective and broadly applicable optimizer for large-scale LLM training. The code is released on https://github.com/jie040109/Conda
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