Virtualization Performance –Real-time Environments vs. Server Environments

Most users today consider Virtualization as it is applied to the server space. VMWare takes the dominant position in this market. But Virtualization for real-time systems requires a distinctly different set of characteristics. The environment is very different and thus requires a different approach. The Virtual Logix value proposition focuses on virtualization for real-time and network systems. Real-time systems require general purpose OS (GPOS) and real-time OS (RTOS) support. There are tradeoff requirements between performance and isolation of processes. In the server environment it’s all about I/O throughput. In the real-time world, latency, timing, and determinism are also important. In the server world, device drivers consist of disks and networks while in the real-time world there are many types of device drivers including both virtual and physical.

Another difference is the heavy set of Windows-based drivers from the 1990s. For companies with legacy software built in the Windows-era virtualization reuses those drivers without having to rewrite them in Linux, real-time, Macintosh OS, or any other OS. Performance can also be enhanced by applying a unique set of security, redundancy, and management tools on each core. For sensitive information, high security could be applied to one core, while for performance a different set of management criteria could be applied to another. Server environments focus often on security while real-time systems focus more often on performance.

Since performance is a key issue in deploying virtualization in an application, it’s interesting to look at the benchmarks. Fundamentally, adding more layers of software would indicate more overhead and to certain extent that’s the case with virtualization technology. The overhead for an arithmetic/floating point calculation is about 1% for Windows-based system. For multi core efficiency there’s a 7% hit and for physical disk reads there’s no overhead. In some ways that’s not too much of a hit.

Best regards,
Hall T.