RT preempt vs RTAI vs Xenomai for Linux in real time

Question

What are the differences, pros and cons of the three real-time OS related OSs, extensions or patches?

I want to measure the processor’s timestamp counter (TSC), the time in nanoseconds each time a data frame or Ack Wifi frame is transmitted or received.

And I realized that improving accuracy and reducing jitter requires one of three real-time technologies because of proactive, interruption, and contextual changes.

I am currently applying RTAI to the kernel. Since it takes a long time to compile, I would like to read something about these three.

Could you recommend some documents or explain about this?

Answer 1

I found an interesting document comparing Xenomai vs Preempt-RT with the basic GPIO test (against the original kernel).

https://www.osadl.org/fileadmin/dam/rtlws/12/Brown.pdf

Xenomai has better overall performance (less jitter), but using this will result in you changing the custom driver using a specific RTDM api. On the other hand, since Preempt RT is not in the main kernel, it is less tested and you may also have problems.

(Xenomai3 actually has two approaches: either use a real-time microkernel to control threads and interruptions in real-time, or if you need less performance using it with a single preempt-rt core)