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Increasing demands in processing power for real-time systems have been met by adding more cores to embedded architectures. However, conventional programming languages lack adequate support for parallelism with real-time constraints. To fill this gap, add-on design tools have been created, often paired with real-time operating systems, to establish temporal guarantees, but they lack native language support for expressing parallelism at a combination of coarse and fine levels. OpenMP would be a good fit to specify such parallelism as it comes with mature compiler and runtime technology for mapping concurrency to execution units via the operating system. However, OpenMP lacks real-time support for scheduling and synchronization under deadline constraints. We analyze the suitability of existing OpenMP for coarse-grained parallelism of real-time systems and identify key points that prevent it from being used as-is. We develop a framework, OpenMP-RT, which aims to address these shortcomings by creating a real-time task construct, with a focus on periodic tasks, along with a robust specification for parallel real-time applications utilizing OpenMP-RT, including support for time-predictable lock-free inter-task communication across priority levels. We implement OpenMP-RT in the LLVM C compiler under OpenMP 5.1. We develop a test suite based on a variety of benchmarks with real-time constraints and demonstrate the correctness and ease of use of our OpenMP-RT implementation, as well as the performance and predictability of multiple different paradigms for inter-task communication.
McDonald et al. (Thu,) studied this question.