Win: Weight-Decay-Integrated Nesterov Acceleration for Adaptive Gradient Algorithms

Pan Zhou, Xingyu Xie, Shuicheng YAN

Keywords: deep learning optimizer

TL;DR: We propose an effective Weight-decay-Integrated Nesterov acceleration for adaptive algorithms to enhance their convergence speed

Abstract: Training deep networks on increasingly large-scale datasets is computationally challenging. In this work, we explore the problem of ``\textit{how to accelerate the convergence of adaptive gradient algorithms in a general manner}", and aim at providing practical insights to boost the training efficiency. To this end, we propose an effective {Weight-decay-Integrated Nesterov acceleration} (Win) for adaptive algorithms to enhance their convergence speed. Taking AdamW and Adam as examples, we minimize a dynamical loss per iteration which combines the vanilla training loss and a dynamic regularizer inspired by proximal point method (PPM) to improve the convexity of the problem. Then we respectively use the first- and second-order Taylor approximations of vanilla loss to update the variable twice while fixing the above dynamic regularization brought by PPM. In this way, we arrive at our Win acceleration (like Nesterov acceleration) for AdamW and Adam that uses a conservative step and a reckless step to update twice and then linearly combines these two updates for acceleration. Next, we extend this Win acceleration to LAMB and SGD. Our transparent acceleration derivation could provide insights for other accelerated methods and their integration into adaptive algorithms. Besides, we prove the convergence of Win-accelerated adaptive algorithms and justify their convergence superiority over their non-accelerated counterparts by taking AdamW and Adam as examples. Experimental results testify the faster convergence speed and superior performance of our Win-accelerated AdamW, Adam, LAMB and SGD over their vanilla counterparts on vision classification tasks and language modeling tasks with CNN and Transformer backbones.