Browsing by Author "Cerqueira, Felipe"
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- Correspondence article: a correction of the reduction-based schedulability analysis for APA schedulingPublication . Cerqueira, Felipe; Brandenburg, Björn B.; Nelissen, GeoffreyIn this correspondence letter, we document and correct a flaw in the reduction-based analysis for real-time scheduling with arbitrary processor affinities (APA). To provide further confidence, the corrected claims have been formalized and machine-checked using the Coq proof assistant.
- On Strong and Weak Sustainability, with an Application to Self-Susp ending Real-Time TasksPublication . Cerqueira, Felipe; Nelissen, Geoffrey; B. Brandenburg, BjörnMotivated by an apparent contradiction regarding whether certain scheduling policies are sustainable, we revisit the topic of sustainability in real-time scheduling and argue that the existing definitions of sustainability should be further clarified and generalized. After proposing a formal, generic sustainability theory, we relax the existing notion of (strongly) sustainable scheduling policy to provide a new classification called weak sustainability. Proving weak sustainability properties allows reducing the number of variables that must be considered in the search of a worst-case schedule, and hence enables more efficient schedulability analyses and testing regimes even for policies that are not (strongly) sustainable. As a proof of concept, and to better understand a model for which many mistakes were found in the literature, we study weak sustainability in the context of dynamic self-suspending tasks, where we formalize a generic suspension model using the Coq proof assistant and provide a machine-checked proof that any JLFP scheduling policy is weakly sustainable with respect to job costs and variable suspension times.