User-driven scheduling of interactive virtual machines

We are developing a distributed computing system, Virtuoso, which presents virtual machines (VMs) as its fundamental abstraction to end users. Long-running noninteractive VMs may coexist on the same host used to support VMs being used by highly interactive users. We must simultaneously provide high average computation rates to the noninteractive VMs while keeping the users of the interactive VMs happy. We report here an initial work on using direct user feedback to achieve this balance. The user is provided with a (physical or logical) button that can be pressed when he feels his machine is responding inadequately. In response, the scheduler boosts the priority of his VMs relative to the other VMs in the system. The priority then declines with time. The goal of the control algorithm driven by this mechanism is to maintain a targeted average time between button presses while simultaneously delivering a high compute rate to the other VMs.