In a large embedded real-time system, priority assignment can greatly affect the timing behavior - which can consequently affect the overall behavior - of the system. Thus, it is crucial for model-based design of a la...
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In a large embedded real-time system, priority assignment can greatly affect the timing behavior - which can consequently affect the overall behavior - of the system. Thus, it is crucial for model-based design of a large embedded real-time system to be able to intelligently assign priorities such that tasks can meet their deadlines. In this paper, we propose a priority-refinement method for dependent tasks distributed throughout a heterogeneous multiprocessor environment. In this method, we refine an initial priority assignment iteratively using the simulated annealing technique with tasks' latest completion times (LCT). Our evaluations, based on randomly-generated models, have shown that the refinement method outperforms other priority-assignment schemes and scales well for large, complex, real-time systems. This method has been implemented in the Automatic Integration of Reusable Embedded Software (AIRES) toolkit and has been successfully applied to a vehicle system control application.
Small low-cost sensor devices with limited resources are being used widely to build a self-organizing wireless network for various applications, such as situation monitoring and asset surveillance. Making such a senso...
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The medium access protocol of Ethernet, CSMA/CD, has an inherent limitation in providing real-time guarantees. Since Ethernet is the most commonly used local area network (LAN) technology due to its low cost, high ban...
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This paper proposes a novel coordinated aggregate scheduling (CAS) algorithm that combines both EOF (earliest-deadline-first) scheduling and rate-based fair queueing. CAS uses guaranteed rate (GR) scheduling (Goyal, P...
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This paper proposes a novel coordinated aggregate scheduling (CAS) algorithm that combines both EOF (earliest-deadline-first) scheduling and rate-based fair queueing. CAS uses guaranteed rate (GR) scheduling (Goyal, P et al., 1995) for traffic aggregates at the inter-aggregate level, but employs EDF-like scheduling at the intra-aggregate level. Computation of the deadline D/sub N/ of a packet at an intermediate node N is coordinated between the node N and its upstream nodes, and D/sub N/ is related to the packet's guaranteed rate clock (GRC) value at the flow-aggregation node. CAS provides tighter end-to-end (e2e) delay bounds than the "vanilla" GR aggregate scheduling that relies on FIFO queueing within an aggregate. Our in-depth simulation results demonstrate CAS's superior performance. Moreover, as an aggregate-based work-conserving scheduling algorithm, CAS incurs lower scheduling and state-maintenance overheads at routers than per-flow scheduling. These salient features make CAS very attractive for use in Internet core networks.
Allocating software components while meeting multiple platform resource constraints is crucial for model-based design of large embedded real-time software and automatic design model transformation. In this paper, we p...
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Allocating software components while meeting multiple platform resource constraints is crucial for model-based design of large embedded real-time software and automatic design model transformation. In this paper, we propose a new method for component allocation using an informed branch-and-bound and forward checking mechanism subject to a combination of resource constraints. We have implemented this method in the automatic integration of reusable embedded software (AIRES) toolkit - which has been developed under the DARPA MoBIES Program - and applied it to an automotive electronic throttle control (ETC) system. Our evaluation based on randomly-generated design models has shown that the proposed method scales well for large and complex embedded real-time software.
Embedded real-time systems are ubiquitous in modern society, many of which perform safety-critical functions, and therefore, it is imperative to have tools and techniques that can guarantee a high degree of system cor...
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We describe an end-to-end tool-chain for model-based design and analysis of component-based embedded real-time software. All aspects of an embedded real-time system are captured in domain-specific models, including so...
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The model-based methodology has proven to be effective for fast and low-cost development of embedded software. In the model-based development process, transforming a software structural model that describes the underl...
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Embedded real-time systems are ubiquitous in modern society, many of which perform safety-critical functions, and therefore, it is imperative to have tools and techniques that can guarantee a high degree of system cor...
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Embedded real-time systems are ubiquitous in modern society, many of which perform safety-critical functions, and therefore, it is imperative to have tools and techniques that can guarantee a high degree of system correctness. They typically perform information processing on a digital computer tightly coupled with the continuous physical environment. Even though hybrid systems is an active research area, most work has ignored the scheduling behavior of software processes due to contention for the shared CPU resource. We propose an integrated approach based on hybrid automata and model-checking for modeling and analysis of computer-based embedded control systems where real-time scheduling behavior of the controller software is explicitly represented at the model-level, together with the physical environment that it interacts with. An application example is used to demonstrate the benefits of the integrated approach in performing tradeoff analysis involving both the controller software and the controlled physical system.
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