TicTac: Accelerating Distributed Deep Learning with Communication Scheduling

Part of Proceedings of Machine Learning and Systems 1 (MLSys 2019)

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Sayed Hadi Hashemi, Sangeetha Abdu Jyothi, Roy Campbell


State-of-the-art deep learning systems rely on iterative distributed training to tackle the increasing complexity of models and input data. In this work, we identify an opportunity for accelerating distributed DNN training in systems that rely on graph representation for computation, such as TensorFlow and PyTorch, through communication scheduling. We develop a system, TicTac, that reduces the iteration time by identifying and enforcing parameter transfers in the order in which the parameters are consumed by the underlying computational model, thereby guaranteeing near-optimal overlap of communication and computation. Our system is implemented over TensorFlow and enforces the optimal ordering by prioritization of parameter transfers at the Parameter Server in data parallel training. TicTac requires no changes to the model or developer inputs and improves the throughput by up to $37.7\%$ in inference and $19.2\%$ in training, while also reducing straggler effect by up to $2.3\times$. Our code is publicly available.