Scheduling I/O in virtual machine monitors

This paper explores the relationship between domain scheduling in a virtual machine monitor (VMM) and I/O performance. Tradition-ally, VMM schedulers have focused on fairly sharing the processor resources among domains while leaving the scheduling of I/O re-sources as a secondary concern. However, this can result in poor and/or unpredictable application performance, making virtualiza-tion less desirable for applications that require efficient and consis-tent I/O behavior. This paper is the first to study the impact of the VMM scheduler on performance using multiple guest domains concurrently run-ning different types of applications. In particular, different com-binations of processor-intensive, bandwidth-intensive, and latency-sensitive applications are run concurrently to quantify the impacts of different scheduler configurations on processor and I/O perfor-mance. These applications are evaluated on 11 different scheduler configurations within the Xen VMM. These configurations include a variety of scheduler extensions aimed at improving I/O perfor-mance. This cross product of scheduler configurations and applica-tion types offers insight into the key problems in VMM scheduling for I/O and motivates future innovation in this area