Embedded Systems Design - August 2008 - (Page 28)

0808esd.p27to29 7/17/08 11:52 AM Page 28 feature rameters 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. BENCHMARKING HYPERVISORS To ensure a level playing ﬁeld for the benchmarking process, all the benchmark suites and kernels must be executed in the CPU’s unprivileged execution environment so that any required system calls must be made through the hypervisor’s API. This is required to meet the basic security deﬁnition of a hypervisor. All the benchmark kernels that are used as the workloads must be executed in isolated virtual machines with the scheduler alternating execution among the virtual machines at least every 10ms. This is required to measure the impact of the VM switching time. But there are no restrictions on the CPU implementation. It can be singlecore, multicore, multithreaded, or any combination. What is necessary is that the CPU must have at least two privileged modes of operation to provide isolation of virtual machines from the hypervisor. This also means the CPU must have a MMU or MPU to enable VM-to-VM isolation, which limits the range of single processors that can be assessed. This is not an assessment of the processor, the multicore implementation, or the communications links themselves, all of which can have an impact on the performance of the software. Rather, the benchmarks are designed to test the implementation and performance of a particular hypervisor on a particular processor or multiprocessor device. BENCHMARKS The aim of the benchmarks is to provide comparisons on the same processor and in the same software environment and to conﬁne themselves to demonstrating the overhead associated with the hypervisor implementation. EEMBC’s testing environment uses three different scenarios to test the sys- Software Development Tools The Leader in Microcontroller Development Solutions C/C++ Development Kit including best-in-class compilers, genuine Keil μVision®, and royalty-free RTX RTOS ULINK®2 Adapter for target debugging and Flash programming ARM www.keil.com/arm A/D I/O Ports RunControl Debug Channel Flash ROM Timers Interrupts Cx51 www.keil.com/c51 PWM UART 2 CPU RAM RTC DMA I C/SPI C166 www.keil.com/c166 Out-of-the box support for more than 1,400 Microcontroller devices Ethernet SD USB CAN Keil RTOS and Middleware components are specifically optimized for embedded systems and include TCP/IP, Flash File system, USB and CAN support Call 1-800-348-8051 for a free demo CD AUGUST 2008 | embedded systems design | www.embedded.com www.keil.com 28 http://www.keil.com http://www.keil.com/arm http://www.keil.com/c51 http://www.keil.com/c166 http://www.keil.com http://www.embedded.com

Table of Contents Feed for the Digital Edition of Embedded Systems Design - August 2008

Embedded Systems Design - August 2008 Contents Number Include Parity Bit Programmer's Toolbox Cover Feature: Virtualization for Embedded X86 Multiprocessor Applications Wanted: Industry Standards for Benchmarking Embedded VMM Hypervisors Achieving Cache Coherence in a MIPS32 Multicore Design Memory Allocation in C Advertising Index Break Points Marketplace

Embedded Systems Design - August 2008

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