Xen and Co.: communication-aware CPU scheduling for consolidated Xen-based hosting platforms

Recent advances in software and architectural support for server virtualization have created interest in using this tech-nology in the design of consolidated hosting platforms. Since virtualization enables easier and faster application migra-tion as well as secure co-location of antagonistic applica-tions, higher degrees of server consolidation are likely to re-sult in such virtualization-based hosting platforms (VHPs). We identify a key shortcoming in existing virtual machine monitors (VMMs) that proves to be an obstacle in operating hosting platforms, such as Internet data centers, under con-ditions of such high consolidation: CPU schedulers that are agnostic to the communication behavior of modern, multi-tier applications. We develop a new communication-aware CPU scheduling algorithm to alleviate this problem. We im-plement our algorithm in the Xen VMM and build a proto-type VHP on a cluster of servers. Our experimental evalu-ation with realistic Internet server applications and bench-marks demonstrates the performance/cost benefits and the wide applicability of our algorithms. For example, the TPC-W benchmark exhibited improvements in average response times of up to 35 % for a variety of consolidation scenarios. A streaming media server hosted on our prototype VHP was able to satisfactorily service up to 3.5 times as many clients as one running on the default Xen