An Analysis of Driver Domain Offload for Paravirtualized Communication

Server virtualization has become a key technology for IT infrastructure due to the efficiency and cost effectiveness that it offers. At the same time, it also poses new challenges for the I/O performance, which has become a major issue of current virtualization. Considering the trend in modern processors which puts more cores into a single-chip, using side-cores to off-load I/O tasks rather than costly special hardware is a promising way to reduce the overhead. In this paper, we examine the network performance of Xen and profile network processing in order to understand the current state of Xen network interface virtualization and speculate the further possibility of off-loading network I/O virtualization overhead using side-cores. Our experiment results show that using side-cores for driver domain offload can significantly improve the network performance of Xen and application throughput for both inter-and intra-node communications. Surprisingly, much of the performance benefit arises from the significant reduction of cache misses due to offload. Our analysis of I/O overheads under virtualization shows that some hypervisor and user domain functions could also be fruitfully off-loaded.