Virtual Machine Performance Benchmarking

Abstract

The attractions of virtual computing are many: reduced costs, reduced resources and simplified maintenance. Any one of these would be compelling for a medical imaging professional attempting to support a complex practice on limited resources in an era of ever tightened reimbursement. In particular, the ability to run multiple operating systems optimized for different tasks (computational image processing on Linux versus office tasks on Microsoft operating systems) on a single physical machine is compelling. However, there are also potential drawbacks. High performance requirements need to be carefully considered if they are to be executed in an environment where the running software has to execute through multiple layers of device drivers before reaching the real disk or network interface. Our lab has attempted to gain insight into the impact of virtualization on performance by benchmarking the following metrics on both physical and virtual platforms: local memory and disk bandwidth, network bandwidth, and integer and floating point performance. The virtual performance metrics are compared to baseline performance on “bare metal.” The results are complex, and indeed somewhat surprising.

Appendix

Fig. 2

The program “benchmark.pl” coordinates the tests and reporting of our Linux testing appliance. The “dd” command is used to measure Input/Output performance of files write to memory, local or remotely network disks. The Dhrystone2 and Whetstone metrics measure integer (billions of operations per second) and floating point performance (millions of operations per second), respectively