| 1. |
- Boudjadar, Abdeldjalil, et al.
(författare)
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A reconfigurable framework for compositional schedulability and power analysis of hierarchical scheduling systems with frequency scaling
- 2015
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Ingår i: Science of Computer Programming. - : ELSEVIER SCIENCE BV. - 0167-6423 .- 1872-7964. ; 113, s. 236-260
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a compositional framework for the modeling and analysis of hierarchical scheduling systems. We consider both schedulability and energy consumption of individual components, while analyzing a single core setting with a voltage frequency scaling CPU. According to the CPU frequency scaling, each task has a set of different execution times. Thus, the energy consumption of the whole system varies from one execution to another. We analyze each component individually by checking the feasibility of its workload against both the CPU availability and energy consumption constraints of such a component. Our periodic task model considers both static and dynamic priorities together with preemptive and non-preemptive behaviors. The models are realized using different forms of Hybrid Automata, all of which are analyzed using variants of UPPAAL. The CPU frequencies, task behavior and scheduling policies used in each component are some of the reconfigurable parameters of the system. Finally, we demonstrate the applicability and scalability of our framework by analyzing the schedulability and power consumption of an avionics system. (C) 2015 Elsevier B.V. All rights reserved.
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| 2. |
- Boudjadar, Abdeldjalil, 1983-, et al.
(författare)
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Statistical and exact schedulability analysis of hierarchical scheduling systems
- 2016
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Ingår i: Science of Computer Programming. - : Elsevier. - 0167-6423 .- 1872-7964. ; 127, s. 103-130
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Tidskriftsartikel (refereegranskat)abstract
- This paper contains two contributions: 1) A development methodology involving two techniques to enhance the resource utilization and 2) a new generic multi-core resource model for hierarchical scheduling systems.As the first contribution, we propose a two-stage development methodology relying on the adjustment of timing attributes in the detailed models during the design stage. We use a lightweight method (statistical model checking) for design exploration, easily assuring high confidence in the correctness of the models. Once a satisfactory design has been found, it can be proved schedulable using the computation costly method (symbolic model checking). In order to analyze a hierarchical scheduling system compositionally, we introduce the notion of a stochastic supplier modeling the supply of resources from each component to its child components in the hierarchy. We specifically investigate two different techniques to widen the set of provably schedulable systems: 1) a new supplier model; 2) restricting the potential task offsets.We also provide a way to estimate the minimum resource supply (budget) that a component is required to provide. In contrast to analytical methods, we prove non-schedulable cases via concrete counterexamples. By having richer and more detailed scheduling models this framework, has the potential to prove the schedulability of more systems.As the second contribution, we introduce a generic resource model for multi-core hierarchical scheduling systems, and show how it can be instantiated for classical resource models: Periodic Resource Models (PRM) and Explicit Deadline Periodic (EDP) resource models. The generic multi-core resource model is presented in the context of a compositional model-based approach for schedulability analysis of hierarchical scheduling systems.The multi-core framework presented in this paper is an extension of the single-core framework used for the analysis in the rest of the paper.
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| 3. |
- Kim, Jin-Hyun, et al.
(författare)
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Optimizing the Resource Requirements of Hierarchical Scheduling Systems
- 2016
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Ingår i: SIGBED Review. - : Association for Computing Machinery (ACM). - 1551-3688 .- 1551-3688. ; 13:3, s. 41-48
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Compositional reasoning on hierarchical scheduling systems is a well-founded formal method that can construct schedulable and optimal system configurations in a compositional way. However, a compositional framework formulates the resource requirement of a component, called an interface, by assuming that a resource is always supplied by the parent components in the most pessimistic way. For this reason, the component interface demands more resources than the amount of resources that are really sufficient to satisfy sub-components. We provide two new supply bound functions which provides tighter bounds on the resource requirements of individual components. The tighter bounds are calculated by using more information about the scheduling system.We evaluate our new tighter bounds by using a model-based schedulability framework for hierarchical scheduling systems realized as Uppaal models. The timed models are checked using model checking tools Uppaal and Uppaal SMC, and we compare our results with the state of the art tool CARTS.
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