Real-time capabilities of Linux RTAI

This article deals with the Linux real-time extension RTAI. This extension provides soft real-time capabilities in the user space and hard real-time capabilities in the kernel space. In this work, some key parameters of the RTOS are measured such as switching context time, periodic thread jitter, interrupt latency response, execution time of synchronization primitives and heap allocation time. This measurements create a test bench of real-time system capabilities which should help the developer to create truly real-time application on the specific hardware based on measured real-time capabilities. RTAI functions can be called from the user space using LXRT and also from the kernel space. These two spaces are compared from the point of view of the developer and real-time capabilities. All measurements have been done on the LinuxCNC 2.7 based on Debian 3.4 distribution running on AMD Athlon XP 3000+ uniprocessor. To accomplish these measurements, new benchmark application has been developed.