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Scratchpad memory (SPM) is a promising on-chip memory choice in real-time and cyber-physical systems where timing is of the utmost importance. SPM has time-predictable characteristics since its data movement between the SPM and the main memory is entirely managed by software. One way of such management is dynamic management. In dynamic management of instruction SPMs, code blocks are dynamically copied from the main memory to the SPM at runtime by executing direct memory access (DMA) instructions. Code management techniques try to minimize the overhead of DMA operations by finding an allocation scheme that leads to efficient utilization. In this article, we present three function-level code management techniques. These techniques perform allocation at the granularity of functions, with the objective of minimizing the impact of DMA overhead to the worst-case execution time (WCET) of a given program. The first technique finds an optimal mapping of each function to a region using integer linear programming (ILP), whereas the second technique is a polynomial-time heuristic that is suboptimal. The third technique maps functions directly to SPM addresses, not using regions, which can further reduce the WCET. Based on ILP, it can also find an optimal mapping. We evaluate our techniques using the Mälardalen WCET suite, MiBench suite, and proprietary automotive applications from industry. The results show that our techniques can significantly reduce the WCET estimates compared to caches with the state-of-the-art cache analysis. [ABSTRACT FROM AUTHOR]

Standby-sparing is one of the common techniques in order to design fault-tolerant safety-critical systems where the high level of reliability is needed. Recently, the minimization of energy consumption in embedded systems has attracted a lot of concerns. Simultaneous considering of high reliability and low energy consumption by DVS is a challenging problem in designing such a system, since using DVS has been shown to reduce the reliability profoundly. In this article, we have studied different schemes of standby-sparing systems from the energy consumption and reliability point of view. Moreover, we propose a new standby-sparing scheme which addresses both reliability and energy consumption jointly together. This scheme uses a simple energy management coupled with an online task scheduler which tries to dispatch those ready tasks which are expected to lead to high reliability and low energy consumption in the system. The effectiveness of the proposed scheme has been shown on TGFF under stochastic workloads. The results show 52% improvement on energy saving compared to the conventional hot standby-sparing system. Moreover, two orders of magnitude higher reliability is obtained on average, while preserving the same level of energy saving as compared to the state-of-the-art low-energy standby-sparing system (LESS). [ABSTRACT FROM AUTHOR]