Aspect-Oriented Customization of the Scheduling Algorithm and the Resource Access Protocol of a Real-Time Operating System

Tasks of an embedded system application are managed by a real-time operating system (RTOS). Most RTOSs adopt just fixed priority scheduling, which is not optimal in all cases. Some applications require earliest deadline first (EDF) scheduling, which is an optimal scheduling algorithm. In order to develop an efficient real-time embedded system, the scheduling algorithm of a RTOS should be selectable. The paper presents a method to customize the scheduling algorithm and the resource access protocol of an OSEK OS using aspect-oriented programming. We define aspects to replace the fixed priority scheduling mechanism of the OSEK OS with an EDF scheduling mechanism. We also define aspects to replace the resource access protocol of the OSEK OS with the resource access protocol for EDF scheduling. By using the aspects, we can customize the scheduling algorithm and the resource access protocol without modifying the original source code. This improves the maintainability of the source code of a RTOS. We have applied the aspects to the OSEK OS and have got a customized RTOS with EDF scheduling. The evaluation results show that the overhead of aspect-oriented programming is small enough.