Nem: Toward Fine-grained Load Balancing through RNIC EC Offloading

Modern datacenter networks employ Load-balancing (LB) in the large-scale multi-tier topology to ensure high network utilization as well as low flow completion time. This paper presents the design and evaluation of Nem, a robust Erasure Coding (EC) based load balancing scheme at end-host to spread data across multiple paths. Our design is based on two key insights. First, both theory and implementation have shown that redundancy is a powerful technique to reduce latency in networked system. Second, the commercial RDMA network interface card supports EC offload which can dramatically reduce the CPU consumption. Nem is an optimal user-level LB design, which leveraging redundant fine-grained data blocks and high speed lossless RDMA network to realize effective load balancing transmission. Evaluation over many workloads shows that Nem is adaptive to the asymmetric networks, and achieves better performance compared to the state-of-art host-based load balancing mechanism.