A comparison between Linux approaches for soft real-time applications

The growth of the use of the Linux operating system in embedded systems projects brings to the spotlight essential questions about the capabilities of this operating system in real-time systems, in particular, soft real-time systems. In this context, the quantitative analysis of Linux-based embedded systems is the focus of this paper, which includes the evaluation of the latency time, jitter, and worst-case response time. Therefore, using a signal generator, a logic analyzer, and a single-board computer, this paper implements a computational routine that interfaces with the General Purpose Input/Output (GPIO) of the embedded system, replying to the stimuli generated by the signal generator. These routines were implemented in User Space and Kernel Space on a Linux-based distribution and, also, for PREEMPT\_RT and Xenomai real-time patches. The result is a holistic comparison between those Linux approaches showing that, although Xenomai outperformed the others and can be applied for hard real-time applications, all the analyzed approaches can be applied for soft real-time applications depending on the project requirements and development constraints.