A well-illustrated technical paper comparing RTLinux, RTAI, and VRTXsa has been published by two Italian computer science students. Emanuele Mattei and Andrea Ludiciani conclude that the RTOSes offer comparable predictability, while RTLinux is the least variable and RTAI the most efficient.

Mattei and Ludiciani just received degrees from the University of Rome La Sapienza. They prepared their paper as a thesis project, then translated itto English in order to share it with LinuxDevices readers. The paper is notable for its interesting and plentiful info-graphics showing the results of both hardware and software performance tests.

The paper sets out to explore the possibility of migrating an embedded telecommunications board from VRTXsa to Linux. RTOS performance characteristics that are explored include:

• Combined hardware latency and interrupt latency
• Latency times of a call that writes 4 bytes of data to a FIFO queue
• Time spent to write and read a 4-byte data block to and from a FIFO queue
• The latency of calls writing 16-byte data blocks to a mailbox, and moving messages from one mailbox to another

The software tests were done in multiple iterations, with varying kernel and userspace loads on the test hardware. The translated Italian is a little rough in some places, but the nicely done infographics should be clear enough.

Click here to download the entire paper as a PDF file:

 
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