WCET and Mixed-Criticality: What does Confidence in WCET Estimations Depend Upon?
نویسندگان
چکیده
Mixed-criticality systems integrate components of different criticality. Different criticality levels require different levels of confidence in the correct behavior of a component. One aspect of correctness is timing. Confidence in worst-case execution time (WCET) estimates depends on the process by which they have been obtained. A somewhat naive view is that static WCET analyses determines safe bounds in which we can have absolute confidence, while measurement-based approaches are inherently unreliable. In this paper, we refine this view by exploring sources of doubt in the correctness of both static and measurement-based WCET analysis. 1998 ACM Subject Classification C.3 Computer Systems Organization – Real-Time and Embedded Systems
منابع مشابه
Real-time Scheduling of Mixed-critical Workloads upon Platforms with Uncertainties
ZHISHAN GUO : Real-Time Scheduling of Mixed-Critical Workloads upon Platforms with Uncertainties (Under the direction of Sanjoy K. Baruah) In designing safety-critical real-time systems, there is an emerging trend in moving towards mixed-criticality (MC), where functionalities with different degrees of importance (i.e., criticality) are implemented upon a shared platform. Since 2007, there has ...
متن کاملMixed-criticality job models: a comparison
The Vestal model [6] in widely used in the realtime scheduling community for representing mixed-criticality real-time workloads. This model requires that multiple WCET estimates – one for each criticality level in a system – be obtained for each task. Burns suggests [3] that being required to obtain too many WCET estimates may place an undue burden on system developers, and proposes a simplific...
متن کاملWhat if we would degrade LO tasks in mixed-criticality systems?
Mixed-criticality (MC) systems [1] allow tasks of different importance (or criticality) to be consolidated into a single system. Consolidation facilitates resource sharing (even across criticality levels) and hence bears the potential to reduce the overall amount of resources needed. However, there is a common misconception that recurs in literature about Vestal’s model: the false believe that ...
متن کاملEvaluating Mixed Criticality Scheduling Algorithms with Realistic Workloads
Most work on mixed-criticality scheduling has considered timing-related failures to be independent of one another. In reality this is not true as in many systems the state that caused the original failure will be similar to the state in the next release (job) of the task. Therefore when arguing about the number of jobs that do not meet their deadlines, it is crucial tasks have an appropriate fa...
متن کاملA Framework to Quantify the Overestimations of Static WCET Analysis
To reduce complexity while computing an upper bound on the worst-case execution time, static WCET analysis performs over-approximations. This feeds the general feeling that static WCET estimations can be far above the real WCET. This feeling is strengthened when these estimations are compared to measured execution times: generally, it is very unlikely to capture the worstcase from observations,...
متن کامل