As enterprise computing hardware has become more powerful, largely by virtue of the high-performance multicore products coming out from Intel and AMD, virtualization has become increasingly popular in IT as enterprise software companies have focused on developing ways to use this hardware more effectively both for server consolidation and centralized provisioning of virtual desktop computing environments for employees. This same trend is now moving into the embedded world, as both single and multicore processors become sufficiently powerful and cost effective to support multiple simultaneous applications. The most straightforward way to maximize the utility of the underlying hardware platform is exactly the same as in the enterprise computing case: virtualization.

The impact of hypervisor technology on the overall performance of a system may vary widely, regardless of the performance capabilities of the underlying hardware. Therefore, it's increasingly important to establish a standard method to benchmark different types of hypervisor software in a consistent and repeatable way. The Embedded Microprocessor Benchmark Consortium (EEMBC) is developing such a method that will help system developers choose the best hypervisor for their application and implement the most optimal configuration parameters for their platforms. This method will enable developers to test various critical performance metrics such as interrupt latency and context switching times in different scenarios--including different software workloads and numbers of processor cores--for both micro benchmarks and full-up application-level benchmarks on fully provisioned operating systems.

The essence of a hypervisor
At its most basic level, a hypervisor, also known as a virtual machine monitor (VMM), is virtualization software that allows multiple operating systems or execution environments to run simultaneously on a single physical CPU. It guarantees complete isolation between the virtual machines (VMs) running above it and also guarantees isolation between itself and those VMs.

A hypervisor is not itself a virtual machine. Rather, the hypervisor allows the creation of multiple virtual machines that run independently on a single core or on multiple cores. These VMs in turn can host Java VMs or other operating systems such as Linux, a real-time operating systems from commercial vendors, or even a home-grown scheduler or thin executive.

The key for the embedded systems market is that the hypervisor allows different operating systems to run simultaneously and in isolation from one another on a single common device. While a powerful enabler of a wide variety of technologies in single-core applications, the technique has particular strength when applied to multicore devices as it allows a simple mapping of system resources and permits existing legacy code to run on one processor and operating system while new applications can be written for the new, more complex, environment. This flexibility also enables developers to make use of new, more power-efficient hardware and still reuse their existing tried and tested code.