DX Latency-Based Based Congestion Control for Datacenters
Abstract: Since the advent of datacenter networking, achieving low latency within the network has been a primary goal. Many congestion control schemes have been proposed in recent years to meet the datacenters' unique performance requirement. The nature of congestion feedback largely governs the behavior of congestion control. In datacenter networks, where round trip times are in hundreds of microseconds, accurate feedback is crucial to achieve both high utilization and low queueing delay. Proposals for datacenter congestion control predominantly leverage explicit congestion notification (ECN) or even explicit inin network feedback to minimize the queuing delay. In this paper, we explore latency-based feedback eedback as an alternative and show its advantages over ECN. Against the common belief that such implicit feedback is noisy and inaccurate, we demonstrate that latency-based based implicit feedback is accurate enough to signal a single packet's queuing delay in 110 0 Gb/s networks. Such high accuracy enables us to design a new congestion control algorithm, DX, that performs fine-grained fine control to adjust the congestion window just enough to achieve very low queuing delay while attaining full utilization. Our extensiv extensive e evaluation shows that: 1) the latency measurement accurately reflects the one one-way way queuing delay in single packet level; 2) the latency feedback can be used to perform practical and finefine grained congestion control in high high-speed speed datacenter networks; and 3) DX