Janus: supporting heterogeneous power management in virtualized environments

The cloud servers have routinely adopted machine virtualization for high energy efficiency. Such virtualization notably improves energy efficiency not only through consolidation, but also through Dynamic Voltage/Frequency Scaling (DVFS). Thus, current hypervisors such as Xen and KVM support power management (PM) policies statically or dynamically setting a Voltage/Frequency (V/F) level, similar to ones deployed by the Linux. However, the current hypervisors can promote only a single PM policy (i.e., host governor) per physical core. This poses a unique challenge for VMs sharing a physical core and running applications with opposite runtime characteristics in a time-shared manner (i.e., heterogeneous VMs); note that the consolidation policy often encourages heterogeneous VMs to share a physical core, since such VMs use different resources in the system [2].