A library framework for the POSIX application-defined scheduling proposal

Developing real-time applications using the POSIX standard API guarantees applications portability at the source code level. However, POSIX standard includes just fixed-priority scheduling and it is not always suited to fulfill the requirements of every real-time system. Recently, an API to use application-defined scheduling algorithms in a way compatible with POSIX was proposed. This model allows the implementation of different scheduling policies in a portable way. Nevertheless, this API is more intended for kernel programmers than for real-time application developers. In this paper, a framework for developing and using a library of POSIX compatible application-defined schedulers is proposed. An API based in this framework is presented and some functionality has been added to it, including fault-tolerance capabilities. With the proposed API, a library of application-defined schedulers can be used to develop real-time applications in a consistent and efficient way. The proposal has been implemented in RTLinux along with a library including many scheduling policies and results of the evaluation of the implementation are presented.