Energy harvesting systems have shown their unique benefit of ultra-long operation time without maintenance and are expected to be more prevalent in the era of Internet of Things. However, due to the batteryless nature, they suffer unpredictable frequent power outages. They thus require a lightweight mechanism for crash consistency since saving/restoring checkpoints across the outages can limit forward progress by consuming hard-won energy. For the reason, energy harvesting systems have been designed with a non-volatile memory (NVM) only. The use of a volatile data cache has been assumed to be not viable or at least challenging due to the difficulty to ensure cacheline persistence.

The advent of non-volatile main memory (NVM) enables the development of crash-consistent software without paying storage stack overhead. However, building a correct crash-consistent program remains very challenging in the presence of a volatile cache. This paper presents Witcher, a systematic crash consistency testing framework, which detects both correctness and performance bugs in NVM-based persistent key-value stores and underlying NVM libraries, without test space explosion and without manual annotations or crash consistency checkers. To detect correctness bugs, Witcher automatically infers likely correctness conditions by analyzing data and control dependencies between NVM accesses. Then Witcher validates if any violation of them is a true crash consistency bug by checking output equivalence between executions with and without a crash. Moreover, Witcher detects performance bugs by analyzing the execution traces. Evaluation with 20 NVM key-value stores based on Intel's PMDK library shows that Witcher discovers 47 (36 new) correctness consistency bugs and 158 (113 new) performance bugs in both applications and PMDK.