arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2102.02888cs.LGcs.DC
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1-bit Adam:具有Adam收敛速度的通信高效大规模训练

1-bit Adam: Communication Efficient Large-Scale Training with Adam's Convergence Speed

Microsoft(微软);University of Rochester(罗切斯特大学);ETH Zurich(苏黎世联邦理工学院)

Hanlin Tang, Shaoduo Gan, Ammar Ahmad Awan, Samyam Rajbhandari, Conglong Li, Xiangru Lian, Ji Liu, Ce Zhang, Yuxiong He

摘要:

大型模型(如BERT和GPT-3)的可扩展训练需要基于模型设计、架构和系统功能的仔细优化。从系统的角度来看,通信已经成为一个主要的瓶颈,特别是在具有标准TCP互连的商品系统上,这些标准TCP互连提供有限的网络带宽。通信压缩是减少此类系统上的训练时间的重要技术。最有效的方法之一是误差补偿压缩,即使在1位压缩下也能提供稳健的收敛速度。然而,最先进的误差补偿技术只适用于基本的优化器,如SGD和动量SGD,它们与梯度线性相关。它们不适用于像Adam这样的非线性基于梯度的优化器,后者为BERT等模型提供了最先进的收敛效率和准确性。在本文中,我们提出了1位亚当,减少通信量高达$5\times$,提供更好的可扩展性,并提供相同的收敛速度作为未压缩亚当。我们的关键发现是Adam的方差(非线性项)变得稳定(在预热阶段之后),并且可以用作其余训练(压缩阶段)的固定前提条件。在多达256个GPU上进行的实验表明,1位Adam可以为BERT-Large预训练提供高达$3.3\times$的吞吐量,并为SQuAD微调提供高达$2.9\times$的吞吐量。此外,我们为我们提出的工作提供了理论分析。

英文摘要:

Scalable training of large models (like BERT and GPT-3) requires careful optimization rooted in model design, architecture, and system capabilities. From a system standpoint, communication has become a major bottleneck, especially on commodity systems with standard TCP interconnects that offer limited network bandwidth. Communication compression is an important technique to reduce training time on such systems. One of the most effective methods is error-compensated compression, which offers robust convergence speed even under 1-bit compression. However, state-of-the-art error compensation techniques only work with basic optimizers like SGD and momentum SGD, which are linearly dependent on the gradients. They do not work with non-linear gradient-based optimizers like Adam, which offer state-of-the-art convergence efficiency and accuracy for models like BERT. In this paper, we propose 1-bit Adam that reduces the communication volume by up to $5\times$, offers much better scalability, and provides the same convergence speed as uncompressed Adam. Our key finding is that Adam's variance (non-linear term) becomes stable (after a warmup phase) and can be used as a fixed precondition for the rest of the training (compression phase). Experiments on up to 256 GPUs show that 1-bit Adam enables up to $3.3\times$ higher throughput for BERT-Large pre-training and up to $2.9\times$ higher throughput for SQuAD fine-tuning. In addition, we provide theoretical analysis for our proposed work.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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