Recent Internet-of-Things or Wireless Sensor Network devices are often operated with energy harvesters. As there are no energy storages in those devices, power is not consistently provided to the devices at all times. In such transiently powered systems, in order to keep the system reliable without losing any execution contexts, non-volatile memories (NVMs) are typically used for swift backup/restoration of execution contexts. In this article, we perform a real-time schedulability analysis of the transiently powered processors with NVMs. We first quantitatively characterize the charging and discharging behaviors of the energy harvester and extract the compute capability of the system in time interval domain. Then, based on Real-Time Calculus, we determine whether the given multi-task workload is schedulable or not with respect to the earliest deadline first (EDF) or fixed-priority (FP) scheduling policies. In addition, we study how the choice of the threshold voltage parameter affects the schedulability, then propose a feasible threshold selection algorithm to enhance schedulability. We verify the effectiveness of the proposed technique with extensive simulations. Compared to the naive selection method, the proposed technique always shows improvements in schedulability in various workloads.

中文翻译：

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带有NVM的瞬态供电处理器的实时可调度性分析和增强

最近的物联网或无线传感器网络设备通常与能量收集器一起使用。由于这些设备中没有能量存储，因此无法始终为设备提供稳定的电源。在这样的瞬态供电系统中，为了在不丢失任何执行上下文的情况下保持系统的可靠性，通常将非易失性存储器（NVM）用于执行上下文的快速备份/还原。在本文中，我们对具有NVM的瞬态供电处理器进行了实时可调度性分析。我们首先定量表征能量收集器的充电和放电行为，并提取系统在时间间隔域中的计算能力。然后，基于实时演算，我们根据最早的截止时间优先（EDF）或固定优先级（FP）的调度策略，确定给定的多任务工作负载是否可调度。此外，我们研究了阈值电压参数的选择如何影响可调度性，然后提出了一种可行的阈值选择算法来增强可调度性。我们通过广泛的仿真验证了所提出技术的有效性。与朴素的选择方法相比，所提出的技术在各种工作负载下始终显示出可调度性方面的改进。我们通过广泛的仿真验证了所提出技术的有效性。与朴素的选择方法相比，所提出的技术在各种工作负载下始终显示出可调度性方面的改进。我们通过广泛的仿真验证了所提出技术的有效性。与朴素的选择方法相比，所提出的技术在各种工作负载下始终显示出可调度性方面的改进。