Accurate Congestion Control for RDMA Transfers

Abstract

High-performance interconnects need congestion control to deal with traffic bursts. In this paper, we propose ACCurate, a congestion control protocol that assigns exact maxmin fair rates to flows, without relying on costly per-flow state inside the network. ACCurate keeps the backlogs outside of the network, protects innocent flows, and promptly recovers the flows' rates after congestive episodes. Comparisons with TCP and PAUSE-only RDMA under datacenter-resembling workloads further show that ACCurate provides up to 10x faster flow completion times. ACCurate relies on simple hardware that can be readily implemented inside switches. In our implementation, the additional circuitry needed in a 16×16 switch occupies less than 2% of FPGA resources.

Distributed Congestion Control Based on Utility Function

“…When congestion is low, increases the size of the scheduled queue, allowing more packets to be sent at line speed [14]. The paper 'Accurate Congestion Control for RDMA Transfers' by Dimitris Giannopoulos et al [16] proposes a new congestion control protocol for Remote Direct Memory Access (RDMA) transfers technology that allows two computers to exchange data directly from their memory without involving the operating system or CPU. ACCurate is crafted to embody efficiency and fairness in congestion control.…”

Latency and Throughput Optimization in Modern Networks: A Comprehensive Survey

“…Flow2SL-ITh separates traffic flows in different virtual lanes (VLs) in order to reduce HoL blocking, while the injection rate of congested flows is throttled. ACCurate [303] is a congestion control protocol for RDMA Transfers that assigns max-min fair rates to flows. ACCurate is a scheme suitable for efficient hardware implementation RoCE provides low latency and low CPU usage but it suffers from network stability.…”