Performance analysis of Web application in Xen-based virtualized environment

Virtualization technologies are experiencing a renewed interest for diverse applications such as Cloud computing and server consolidation. These technologies reduce costs and improve flexibility and reliability of services. However, they pose a new performance challenge. An application performance running inside virtual machine may considerably differ from its performance in native one because of the hypervisor overhead and the interference among virtual machines. In this paper, we provide a detailed performance analysis of multi-tier Web application running in Xen environment using CloudStone benchmark and Oprofile/Xenoprof tool to identify the main sources of performance degradation of Web application in Xen. Our experiments indicate that average response time of Web application in Xen is two and one-half times of that in native environment. The detailed analysis of symbol-specific information generated by profiling tools indicates that this large difference in response time is likely due to the most CPU consuming and the highest L2 cache miss functions of Xen that schedule domains on physical cores and of Dom0 kernel which handle the I/O operation of other domains.