Measuring the impact of SR-IOV and virtualization on packet round-trip time

This article explores different data plane configurations for data center servers, focusing on scenarios involving SR-IOV in conjunction with KVM virtualization. Specifically, it evaluates the performance of different ways of using SR-IOV, including MacVTap "passthrough" mode with SR-IOV and PCI Passthrough on the Linux data plane. The study aims to shed light on how SR-IOV can be leveraged to optimize round-trip time (RTT) and resource usage. Through the experiments, we confirmed the expected behaviors of the technology but also clarified and identified behavioral aspects not yet known. For example, we confirmed that SR-IOV could improve RTT and outperform more traditional configurations, but we identified that this comes at the price of utilizing more computational resources, such as the CPU, depending on the orchestrated usage configuration. Furthermore, our evaluations also found that configuring the SR-IOV MacVTap in "passthrough" mode appears to be the best configuration when CPU resources are scarce or low or when scalability and flexibility are design requirements. In this article, we also expanded the SR-IOV assessment regarding the concurrency of this feature. Through these assessments, we identified that a VM without SR-IOV in a data center with other VMs that benefit from SR-IOV is inefficient from a performance point of view of communication. Thus, in this way, this study provides valuable information on how to optimize the use of SR-IOV in KVM environments to design efficient and high-performance virtualized data centers.