The well-known model of Vestal aims to avoid excessive pessimism in the quantification of the processing requirements of mixed-criticality systems, while still guaranteeing the timeliness of higher-criticality functions. This can bring important savings in system costs, and indirectly help meet size, weight and power constraints. This efficiency is promoted via the use of multiple worst-case execution time (WCET) estimates for the same task, with each such estimate characterized by a confidence associated with a different criticality level. However, even this approach can be very pessimistic when the WCET of successive instances of the same task can vary greatly according to a known pattern, as in MP3 and MPEG codecs or the processing of ADVB video streams. In this paper, we present a schedulability analysis for the new multiframe mixed-criticality model, which allows tasks to have multiple, periodically repeating, WCETs in the same mode of operation. Our work extends both the analysis techniques for Static Mixed-Criticality scheduling (SMC) and Adaptive Mixed-Criticality scheduling (AMC), on one hand, and the schedulability analysis for multiframe task systems on the other. A constrained-deadline model is initially targeted, and then extended to the more general, but also more complex, arbitrary-deadline scenario. The corresponding optimal priority assignment for our schedulability analysis is also identified. Our proposed worst-case response time (WCRT) analysis for multiframe mixed-criticality systems is considerably less pessimistic than applying the static and adaptive mixed-criticality scheduling tests oblivious to the WCET variation patterns. Experimental evaluation with synthetic task sets demonstrates up to 20% and 31.4% higher scheduling success ratio (in absolute terms) for constrained-deadline analyses and arbitrary-deadline analyses, respectively, when compared to the best of their corresponding frame-oblivious tests.

中文翻译：

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具有任意期限的多帧混合临界系统的响应时间分析

Vestal 的著名模型旨在避免在量化混合临界系统的处理需求时过度悲观，同时仍然保证较高临界函数的时效性。这可以显着节省系统成本，并间接帮助满足尺寸、重量和功率限制。这种效率是通过对同一任务使用多个最坏情况执行时间 (WCET) 估计来提高的，每个这样的估计都以与不同临界级别相关联的置信度为特征。然而，当同一任务的连续实例的 WCET 可以根据已知模式（如 MP3 和 MPEG 编解码器或 ADVB 视频流的处理）变化很大时，即使这种方法也可能非常悲观。在本文中，我们为新的多帧混合临界模型提供了可调度性分析，该模型允许任务在相同的操作模式下具有多个、周期性重复的 WCET。我们的工作一方面扩展了静态混合临界调度 (SMC) 和自适应混合临界调度 (AMC) 的分析技术，另一方面扩展了多帧任务系统的可调度性分析。受限期限模型最初是针对的，然后扩展到更一般但也更复杂的任意期限场景。还确定了我们的可调度性分析的相应最佳优先级分配。我们针对多帧混合临界系统提出的最坏情况响应时间 (WCRT) 分析比应用静态和自适应混合临界调度测试而忽略 WCET 变化模式的悲观程度要低得多。使用合成任务集进行的实验评估表明，与相应的框架遗忘测试中的最佳测试相比，约束截止时间分析和任意截止时间分析的调度成功率（绝对值）分别高出 20% 和 31.4%。