PROJECT TITLE :

Schedulability Analysis of Hierarchical Real-Time Systems under Shared Resources

ABSTRACT:

Sharing resources in hierarchical real-time systems implemented with reservation servers requires the adoption of special budget management protocols that preserve the bandwidth allocated to a selected element. In addition, blocking times should be accurately estimated to ensure both the world feasibility of all the servers and therefore the local schedulability of applications running on each part. This paper presents 2 new native schedulability tests to verify the schedulability of real-time applications running on reservation servers below fastened priority and EDF local schedulers. Reservation servers are implemented with the BROE algorithm. A simple extension to the SRP protocol is additionally proposed to scale back the blocking time of the server when accessing global resources shared among parts. The performance of the new schedulability tests are compared with different solutions proposed within the literature, showing the effectiveness of the proposed enhancements. Finally, an implementation of the main protocols on a light-weight RTOS is described, highlighting the most practical issues that have been encountered.