Implementing an Application-Defined Scheduling Framework for Ada Tasking

A framework for application-defined scheduling and its correspond-ing application program interface (API) were defined during the last Interna-tional Real-Time Ada Workshop, and are being proposed for standardization in the future revision of the Ada language. The framework allows applications to install one or more task schedulers capable of implementing a large variety of scheduling algorithms. This paper describes the implementation of this frame-work, both at the compiler and the run-time system levels. The objective of this work is to serve as a reference implementation in which the API can be evalu-ated and tested, and its performance can be assessed. We show that the amount of changes to the compiler is relatively small, and that the application scheduling capability can be supported with a small level of complexity.