For precise timing analysis of hard-real applications a predictable memory system is of particular importance. Caches have a great impact on performance, but at the cost of reduced timing predictability. Conventional scratchpads, i.e. statically managed on-chip memories, provide predictable memory accesses, but they are usually badly utilized. Better memory utilization is allowed by dynamically managed scratchpads that are designed for predictability. In this paper we propose a function scratchpad that is dynamically managed in hardware and provides a predictable timing behavior. The function scratchpad exploits a simultaneous multithreaded architecture to increase the pipeline and memory bandwidth utilization while preserving predictability.
Multi-cores are the contemporary solution to satisfy high performance and low energy demands in general and embedded computing domains. However, currently available multi-cores are not feasible to be used in safetycritical environments with hard real-time constraints. Hard real-time tasks running on different cores must be executed in isolation or their interferences must be time-bounded. Thus, new requirements also arise for a real-time operating system (RTOS), in particular if the parallel execution of hard real-time applications should be supported.In this paper we focus on the MERASA 1 system software as an RTOS developed on top of the MERASA multi-core processor. The MERASA system software fulfils the requirements for time-bounded execution of parallel hard real-time tasks. In particular we focus on thread control with synchronisation mechanisms, memory management and resource management requirements. Our evaluations show that all system software functions are time-bounded by a worst-case execution time (WCET) analysis.
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