Stream: Decentralized opportunistic inter-coflow scheduling for datacenter networks

Coflow scheduling can improve application-level communication performance for data-parallel clusters. However, most prior coflow scheduling schemes are based on the centralized approach, which achieve good performance but suffers from high control overhead and scalability issue. On the other hand, state of the art decentralized solution requires switch modification, which makes it hard to implement. In this paper, we present Stream, the decentralized and readilyimplementable solution for coflow scheduling. The key idea of Stream is to opportunistically take advantage of many-to-one and many-to-many coflow patterns to coordinate coflows without resorting to the centralized controller, and then emulate shortest coflow first scheduling to minimize the average coflow completion time (CCT). We implement Stream with existing commodity switches and show its performance using both testbed experiments and large-scale simulations. Our evaluation results show that Stream's performance is comparable to the centralized solution, and outperforms the state of the art decentralized scheme by 1.77x on average.