A paravirtualized file system for accelerating file I/O

Recently, virtualization technologies have gained widespread use in various systems since several new technologies assist virtual machines (VMs) in achieving high performance. However, I/O-intensive workloads still suffer from performance degradation due to CPU mode switching and duplicated I/O stacks in both the guest and host operating systems. In this paper, we propose a framework for improving file I/O performance in a virtualized environment, which consists of a paravirtualized file system, a shared queue, and an I/O-dedicated thread. The key ideas are to handle file I/O requests without the interference of the hypervisor and to have I/O requests bypass the guest I/O stack. To verify the performance improvement of our approach, we implemented a prototype and measured the performance. Experimental results demonstrate that our framework outperforms virtio, the predominant I/O virtualization framework, by providing 1.2-1.6x better throughput and that it eliminates most vmexits during I/O process.