Software Physical/Virtual Rx Queue Mapping Toward High-Performance Containerized Networking

Softwarization of Network Functions (NFs) accelerates automated deployment and management of services on next-gen networks. Combining flexibility and high-performance is a vital requirement for Network Functions Virtualisation (NFV); however, many studies have demonstrated that containerization or virtualization of NFs severely degrades the fundamental efficiency of packet forwarding. Virtual network I/O, a mechanism of packet transferring between a guest and the host, has been seen as the performance bottleneck in the PVP (Physical-Virtual-Physical) datapath, and one of the main causes of this deterioration is packet copy between them. Various techniques, such as zero-copy, pass-through, and hardware offloading, have been examined to alleviate the performance overhead. However, existing designs and implementations incur pragmatic issues, such as compatibility, manageability, and insufficient quality of performance. We propose yet another design and implementation of zero-copy/pass-through acceleration (named IOVTee) to resolve real-world problems as well as to enhance the forwarding efficiency. IOVTee takes advantage of pre-processing of virtual switches with achieving zero-copy on the receive (Rx) path. The pluggable style of IOVTee for vhost-user (the de-facto virtual network I/O) enables our approach to be transparent to both containers/VMs and virtual switches. In this article, we explain the heart of IOVTee, a fully software-based Rx queue mapping mechanism (between physical and virtual) that enables a concept of Virtual DMA Write-through (to the NF). Our evaluation results showed that applying IOVTee to vhost-user drastically increased efficiency of packet forwarding in the PVP datapath (by 45% and 98% for traffic of 64-byte and 1514-byte packets respectively).