Performance consequence of user space file systems due to extensive CPU sharing in virtual environment

Abstract

Recently, FUSE based user space file systems have gained importance due to their ease of implementation. Their lower performance versus implementation benefits, compared to traditional in-kernel file systems, has always been a point of debate among researchers. As FUSE requires additional context switching to perform file related operations, there is a noticeable increase in CPU utilization. In this era of cloud computing, where the focus is shifting on running applications in virtual machines, increased CPU utilization during file operations can have considerable impact on performance, as resources of the hypervisor are shared among virtual machines. This degradation in performance can become a major cause of concern especially when resources are over-committed. There has been ongoing research regarding improvement in performance of user space file systems, and this will help in providing a systematic study on evaluating their performance. For an in-depth examination, we analyzed the performance of FUSE based file systems running in a guest virtual machine and highlighted some of the scenarios, where there could be a major damage to the file system’s performance. We have also showed here, that a careful selection of parameters like block sizes and type of read/write operations can improve performance of these file systems significantly by 40% to 45% even in heavily loaded environment. This study will inspire users and developers to enhance the performance of FUSE based file systems which are now commonly used in cluster of virtual machines.