G-PFC: A Packet-Priority Aware PFC Scheme for the Datacenter

Abstract

Modern datacenter applications demand ultra-low latency and high throughput to meet customer requirements. To achieve good performance, the RoCEv2 (RDMA over Converged Ethernet) protocol, which is based on lossless ethernet, is widely used in large-scale data centers. PFC (Priority-based Flow Control) is a switch-level flow control scheme to support lossless ethernet. However, the typical PFC has a lack of support for the various types of applications that require different QoS for throughput and latency. In this paper, we present G-PFC, a packet-based priority aware flow control scheme to provide low queuing delay and less pause duration for the high priority traffic (packets) that compare to low priority traffic (packets). G-PFC also prevents HoL (Head of Line) blocking problems for the high priority traffics when the congestion is caused by low priority traffics. We ran NS-3 simulations to compare G-PFC and PFC, and the simulation result shows that G-PFC outperforms the PFC in terms of FCT (Flow Completion Time).