SmartNICs have recently emerged as an appealing device for accelerating distributed systems. However, there has not been a comprehensive characterization of SmartNICs, and existing designs typically only leverage a single communication path for workload offloading. This paper presents the first holistic study of a representative off-path SmartNIC, specifically the Bluefield-2, from a communication-path perspective. Our experimental study systematically explores the key performance characteristics of communication among the client, on-board SoC, and host, and offers insightful findings and advice for designers. Moreover, we propose the concurrent use of multiple communication paths of a SmartNIC and present a pioneering guideline to expose new optimization opportunities for various distributed systems. To demonstrate the effectiveness of our approach, we conducted case studies on a SmartNIC-based distributed file system (LineFS) and an RDMA-based disaggregated key-value store (DrTM-KV). Our experimental results show improvements of up to 30% and 25% for LineFS and DrTM-KV, respectively.

翻译：智能网卡近年来作为加速分布式系统的理想设备备受关注。然而，目前尚缺乏对智能网卡的系统性特性分析，现有设计通常仅利用单一通信路径进行工作负载卸载。本文首次从通信路径视角对代表性离路径智能网卡（Bluefield-2）开展系统性研究。通过实验研究，我们系统性地探索了客户端、板载SoC与主机间通信的关键性能特征，为设计人员提供了有价值的发现与建议。此外，我们提出智能网卡多通信路径并发使用的方案，并首创性提出指导准则，为各类分布式系统揭示新的优化机遇。为验证方案有效性，我们在基于智能网卡的分布式文件系统（LineFS）和基于RDMA的解耦键值存储系统（DrTM-KV）上开展案例研究。实验结果表明，LineFS和DrTM-KV的性能分别提升高达30%和25%。