A software-based technique enabling composable hierarchical preemptive scheduling for time-triggered applications

Many embedded real-time applications are typically time-triggered and preemptive schedulers are used to execute tasks of such applications. Orthogonally, composable partitioned embedded platforms use preemptive time-division multiplexing mechanism to isolate applications. Existing composable systems that support two-level scheduling are restricted to cooperative intra-application schedulers, and thus cannot execute the time-triggered applications. In this work, we introduce a framework that allows concurrent, composable execution of such applications on temporally-partitioned systems. The framework is composed of an execution platform and a method for timing analysis of applications running on the platform. The platform realizes a software-based timed-interrupt virtualization technique on an existing composable system. Multiple time-triggered applications may run concurrently using different intra-application preemptive scheduling policies, e.g., fixed-priority and rate-monotonic. The analysis method formalizes the available processing time for executing each application on a processor in order to enable schedulability tests for different policies. Finally, these concepts are demonstrated by executing a number of applications, first on an FPGA prototype and second on a Matlab simulation of the platform. The results indicate a composable and concurrent execution of multiple time-triggered applications using our proposed framework. Furthermore, the implementation of the technique has low cost in terms of memory footprint and execution overhead.