Virtual Battery: A testing tool for power-aware software

Virtualization is an inexpensive and convenient method for setting up software test environments. Thus it is being widely used as a test tool for software products requiring high reliability such as mission critical cyber-physical systems. However, existing virtualization platforms do not fully virtualize the battery subsystem. Therefore, it is difficult to test battery-related features of guest systems. In this paper, we propose Virtual Battery, a battery virtualization scheme for type II full virtualization platforms. Virtual Battery takes the form of an ACPI-compatible battery device driver dedicated to each virtual machine, which virtualizes a target system. Through Virtual Battery, developers can easily manipulate the charging and battery status of each virtual machine (VM), regardless of the existence or current status of the host sys-tem's battery. In addition, Virtual Battery emulates the behavior of batteries by discharging the virtual batteries according to the resource usages of their VMs. This feature enables VMs to act as battery resource containers. Three case studies demonstrate the effectiveness of the proposed scheme. To extend battery lifetime and improve the user experience, most modern operating systems (OSs) employ low-power operating modes that change diverse system behaviors according to battery status, such as the charging/discharging condition and remaining energy. In addition, to protect user and critical system data, most systems automatically save their memory contents to permanent storage devices, suspending their operations until the battery systems are recharged. This is called hibernation. As the importance of battery management in mobile cyber-physical systems is ever increasing, such battery-related software components are becoming more powerful, complicated, and error-prone. Although many debuggers and profilers for application development have been introduced, there are relatively few tools for system software development; therefore, testing and resuscitating specific behaviors exhibited by system software or device drivers remain difficult problems. Emerging virtualization technology significantly relieves this difficulty. By making target systems run on virtual machines (VMs) and by manipulating these VMs, developers can easily observe the behavioral characteristics of target systems as they react to hardware status changes [1,2]. In addition, virtualized target systems enable developers to run multiple target systems or to have different target OSs on a single development workstation at the same time. For a hardware component to be used in a VM, the virtualiza-tion platform must provide the component to the VM as a virtual device. For example, a battery subsystem has to be virtualized and provided to VMs if developers want …