Global Sparse Momentum SGD for Pruning Very Deep Neural Networks Xiaohan Ding 1 Guiguang Ding 1 Xiangxin Zhou 2 Yuchen Guo 1, 3 Jungong Han 4 Ji Liu 5 1 Beijing National Research Center for Information Science and Technology (BNRist); School of Software, Tsinghua University, Beijing, China 2 Department of Electronic Engineering, Tsinghua University, Beijing, China 3 Department of Automation, Tsinghua University; Institute for Brain and Cognitive Sciences, Tsinghua University, Beijing, China 4 WMG Data Science, University of Warwick, Coventry, United Kingdom 5 Kwai Seattle AI Lab, Kwai FeDA Lab, Kwai AI platform
[email protected] [email protected] [email protected] [email protected] [email protected] [email protected] Abstract Deep Neural Network (DNN) is powerful but computationally expensive and memory intensive, thus impeding its practical usage on resource-constrained front- end devices. DNN pruning is an approach for deep model compression, which aims at eliminating some parameters with tolerable performance degradation. In this paper, we propose a novel momentum-SGD-based optimization method to reduce the network complexity by on-the-fly pruning. Concretely, given a global compression ratio, we categorize all the parameters into two parts at each training iteration which are updated using different rules. In this way, we gradually zero out the redundant parameters, as we update them using only the ordinary weight decay but no gradients derived from the objective function. As a departure from prior methods that require heavy human works to tune the layer-wise sparsity ratios, prune by solving complicated non-differentiable problems or finetune the model after pruning, our method is characterized by 1) global compression that automatically finds the appropriate per-layer sparsity ratios; 2) end-to-end training; 3) no need for a time-consuming re-training process after pruning; and 4) superior capability to find better winning tickets which have won the initialization lottery.