Differentiated I/O services in Virtualized environments

There is a huge semantic gap between file system and storage in servicing an I/O request. In a virtual environment the gap increases even more, as the hypervisor’s I/O scheduler is not aware of the semantics of the I/O request that the application issues. To address this limitation and to retain the semantics of the I/O requests in a virtualized environment, we tag each I/O request from the guest application all the way down to the hypervisor’s I/O scheduler. By segregating I/O requests, the hypervisor can give differentiated I/O services to different applications both within and across the guest virtual machines. In this paper, we present the design and implementation of such a system on Kernel Based Virtual Machine. We evaluated our system on hard disks and solid state disks for different workloads. Our results show that preferential services are well achieved for applications running within and across guest virtual machines.