Linux PREEMPT-RT v2.6.33 versus v3.6.6

Abstract

Linux was originally designed as a general purpose operating system without consideration for real-time applications. Recently, it became a more reliable candidate in the real-time field due to its daily improvements, both for general purpose and real-time usages. In this research, we test two Linux PREEMPT-RT versions (v3.6.6 and v2.6.33.7) in the aim of benchmarking its performance and behaviour to give an insight whether the enhancements in its kernel are improving the determinism of the operating system. Our benchmark will be based on the following experimental measurements' metrics: thread switch latency, interrupt latency, sustained interrupt frequency, mutex and semaphore acquisition and release durations, and finally the locking behaviour of mutex. These measurements are executed for each Linux version, on the same x86 platform (ATOM processor) using the same test framework and measurement equipment. Comparing the results show that Linux v3.6.6 has significantly better worst case results which makes the actual Linux PREEMPT-RT version a better candidate for RT-applications. Suggestions are made for further improvements.