From RTAI to RT-Preempt a quantative approach in replacing Linux based dual kernel real-time operating systems with Linux RT-Preempt in distributed real-time networks for educational ICT systems

摘要

Dual Kernel RTOS tend to have a long integration time for new hardware as the internal design of differentiating between real-time and non-real-time Interrupt Requests (IRQ) often creates the need to port hardware drivers like USB, Wifi or others to be able to handle RT-IRQs. This can take a serious amount of setup time which makes frequent changes in the hardware setup or even kernel updates, due to changes in the Kernel API, a tedious and time consuming job. This work gives an example on how to circumvent these problems through migration from such solutions like RTAI or Xenomai to native Linux real-time via the RT-Preempt patch and highlights the shortcomings of said patch via benchmarking. It also shows how to move from TDMA (Time Devision Multiple Access) to packet switching real-time. The approach thereby bridges the gap that Xenomai 3 Mercury currently doesn't fulfill as it is userspace only: the RTAI/Xenomai Kernel API as well as a useful replacement for RTnet. The overall scope thereby lies on creating a foundation for the implementation of a Linux based real-time middleware platform for Industry 4.0 and the IoT.