Evaluating and Optimizing I/O Virtualization in Kernel-based Virtual Machine (KVM)

Abstract

I/O virtualization performance is an important problem in KVM. In this paper, we evaluate KVM I/O performance and propose several optimizations for improvement. First, we reduce VM Exits by merging successive I/O instructions and decreasing the frequency of timer interrupt. Second, we simplify the Guest OS by removing redundant operations when the guest OS operates in a virtual environment. We eliminate the operations that are useless in the virtual environment and bypass the I/O scheduling in the Guest OS whose results will be rescheduled in the Host OS. We also change NIC driver's configuration in Guest OS to adapt the virtual environment for better performance.