Weakly hard real-time systems can, to some degree, tolerate deadline misses, but their schedulability still needs to be analyzed to ensure their quality of service. Such analysis usually occurs at early design stages to provide implementation guidelines to engineers so that they can make better design decisions. Estimating worst-case execution times (WCET) is a key input to schedulability analysis. However, early on during system design, estimating WCET values is challenging and engineers usually determine them as plausible ranges based on their domain knowledge. Our approach aims at finding restricted, safe WCET sub-ranges given a set of ranges initially estimated by experts in the context of weakly hard real-time systems. To this end, we leverage (1) multi-objective search aiming at maximizing the violation of weakly hard constraints in order to find worst-case scheduling scenarios and (2) polynomial logistic regression to infer safe WCET ranges with a probabilistic interpretation. We evaluated our approach by applying it to an industrial system in the satellite domain and several realistic synthetic systems. The results indicate that our approach significantly outperforms a baseline relying on random search without learning, and estimates safe WCET ranges with a high degree of confidence in practical time (< 23h).

翻译：弱实时系统可在一定程度上容忍截止时间错过，但仍需分析其可调度性以保证服务质量。此类分析通常在早期设计阶段进行，为工程师提供实现指导以优化设计决策。最差执行时间（WCET）的估计是可调度性分析的关键输入。然而在系统设计初期，WCET值难以确定，工程师通常依赖领域知识将其估计为合理范围。我们的方法旨在针对弱实时系统，在专家初始估计的范围集合中，寻找受限且安全的WCET子范围。为此，我们利用：（1）多目标搜索技术，通过最大化违反弱实时约束来发现最差调度场景；（2）多项式逻辑回归方法，以概率解释方式推断安全WCET范围。我们通过将该方法应用于卫星领域的工业系统及多个逼真综合系统进行评估。结果表明，与基于随机搜索的无学习基线方法相比，我们的方法显著更优，且能在实际时间限制内（<23小时）以高置信度估计出安全WCET范围。