Optimizing Network Paravirtualization with Static Shared Memory Pipe

Virtual machine technology can provide high server utilization and service consolidation on an individual physical machine, and gains acceptance in diverse fields. In a growing number of contexts, many situations require high-performance network virtualization. Paravirtualized network system adopts split driver model, and uses dynamic shared memory mechanism for communication between unprivileged guest domain and isolated driver domain. The dynamic shared memory mechanism introduces extra per-packet overheads, such as additional hypercalls and grant table operations. In this paper, we have implemented a new method called STAMP (static shared memory pipe), which uses static shared memory mechanism on Xen platform. STAMP comprises a two-way lockless producer-consumer circular buffer to carry network packets between split drivers. Once STAMP is established between guest domain and isolated driver domain, all packets are transferred through it to avoid extra overheads introduced by dynamic shared memory mechanism. In our evaluations, STAMP achieves availability and high efficiency, especially for scenarios of small messages. These results make the static shared memory mechanism an attractive solution for network paravirtualization.