PayDebt: Reduce Buffer Occupancy Under Bursty Traffic on Large Clusters
Kexin Liu, Chen Tian, Qingyue Wang, Yanqing Chen, Bingchuan Tian, Wenhao Sun, Ke Meng, Long Yan, Lei Han, Jie Fu, Wanchun Dou, Guihai Chen · IEEE Transactions on Parallel and Distributed Systems · 2022
The average/tail Flow Completion Times (FCTs) are critical to many datacenter applications. Congestion control plays a central role in optimizing FCT. Inappropriate congestion control can exacerbate buffer occupancy, thus hurting the flow performance. Our observations are that current approaches are too aggressive in injecting packets into underlying networks. Instead of handling buffer explosion afterward, we reduce buffer occupancy in the first place. We propose PayDebt, a novel and readily-deployable proactive congestion control protocol. At its heart, adebtmechanism provides bandwidth coordination between the already-buffered and the forthcoming packets. We evaluate PayDebt both in a testbed and large-scale simulations. The buffer occupancy can be decreased by up to 8.0×-35.9× compared to DCQCN and Homa.