A Performance Evaluation of Multi-Programming Model on a Multicore System with Virtual Machines

For a lot of equipment like industrial equipment, automotive or consumer electrical appliances, embedded computers are widely used. Many computers are embedded in the equipment because it has excellent features and their controls are more complex. Recently, general purpose microcomputer has been made to have multicore CPUs to achieve high performance. Multicore CPU is also expected to be used widely because of embedded computers, but it is not clear how to use the computer. Virtual machine technology is proposed and used as the solution to the problem, as it makes possible the integration of some control computers into a high-performance embedded computer. However, it is not simple for engineers to design the performance of the system because the characteristics of virtual machines are different compared with real machines. In this article, the performance characteristics of multicore embedded computers with virtual machines are analyzed, with an assumption that the control programs are developed by multi-programming model using process or thread of Linux OS. For the evaluations, a benchmark program is designed. The results show a performance difference of 5%-10% between process cases and thread cases, regardless whether real machine or virtual machine is used. In performance comparison of real machine and virtual machine, 13%-88% performance differences are realized, which depend on the number of CPU cores. Furthermore, some unprecedented phenomena in performance are found in cases where the number of CPU cores exceeds the number of parallel executions of process/thread. The measured results are useful and can serve as a guide in designing system performance for multicore embedded computers.