1,045 research outputs found

    DEVELOPMENT OF GENETIC ALGORITHM-BASED METHODOLOGY FOR SCHEDULING OF MOBILE ROBOTS

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    Model-based optimization of ARINC-653 partition scheduling

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    Periodic multiprocessor scheduling

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    From Dataflow Specification to Multiprocessor Partitioned Time-triggered Real-time Implementation *

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    International audienceOur objective is to facilitate the development of complex time-triggered systems by automating the allocation and scheduling steps. We show that full automation is possible while taking into account the elements of complexity needed by a complex embedded control system. More precisely, we consider deterministic functional specifications provided (as often in an industrial setting) by means of synchronous data-flow models with multiple modes and multiple relative periods. We first extend this functional model with an original real-time characterization that takes advantage of our time-triggered framework to provide a simpler representation of complex end-to-end flow requirements. We also extend our specifications with additional non-functional properties specifying partitioning, allocation , and preemptability constraints. Then, weprovide novel algorithms for the off-line scheduling of these extended specifications onto partitioned time-triggered architectures à la ARINC 653. The main originality of our work is that it takes into account at the same time multiple complexity elements: various types of non-functional properties (real-time, partitioning, allocation, preemptability) and functional specifications with conditional execution and multiple modes. Allocation of time slots/windows to partitions can be fullyor partially provided, or synthesized by our tool. Our algorithms allow the automatic allocation and scheduling onto multi-processor (distributed) sys-tems with a global time base, taking into account communication costs. We demonstrate our technique on a model of space flight software systemwith strong real-time determinism requirements

    A Real-time Calculus Approach for Integrating Sporadic Events in Time-triggered Systems

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    In time-triggered systems, where the schedule table is predefined and statically configured at design time, sporadic event-triggered (ET) tasks can only be handled within specially dedicated slots or when time-triggered (TT) tasks finish their execution early. We introduce a new paradigm for synthesizing TT schedules that guarantee the correct temporal behavior of TT tasks and the schedulability of sporadic ET tasks with arbitrary deadlines. The approach first expresses a constraint for the TT task schedule in the form of a maximal affine envelope that guarantees that as long as the schedule generation respects this envelope, all sporadic ET tasks meet their deadline. The second step consists of modeling this envelope as a burst limiting constraint and building the TT schedule via simulating a modified Least-Laxity-First (LLF) scheduler. Using this novel technique, we show that we achieve equal or better schedulability and a faster schedule generation for most use-cases compared to other approaches inspired by, e.g., hierarchical scheduling. Moreover, we present an extension to our method that finds the most favourable schedule for TT tasks with respect to ET schedulability, thus increasing the probability of the computed TT schedule remaining feasible when ET tasks are later added or changed

    Scheduling theory since 1981: an annotated bibliography

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    Time Triggered Scheduling Analysis for Real-Time Applications on Multicore Platforms

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    REACTION 2014. 3rd International Workshop on Real-time and Distributed Computing in Emerging Applications. Rome, Italy. December 2nd, 2014.Scheduling of real-time applications for multicore platforms has become an important research topic. For analyzing the timing satisfactions of real-time tasks, most researches in the literature assume independent tasks. However, industrial applications are usually with fully tangled dependencies among the tasks. Independence of the tasks provides a very nice abstraction, whereas dependent structures due to the tangled executions of the tasks are closer to the real systems. This paper studies the scheduling policies and the schedulabil-ity analysis based on independent tasks by hiding the execution dependencies with additional timing parameters. Our scheduling policy relates to the well-known periodic task model, but in contrast, tasks are able to communicate with each other. A feasible task set requires an analysis for each core and the communication infrastructure, which can be performed indi-vidually by decoupling computation from communication in a distributed system. By using a Time-Triggered Constant Phase (TTCP) scheduler, each task receives certain time-slots in the hyper-period of the task set, which ensures a time-predictable communication impact. In this paper, we provide several algorithms to derive the time-slot for each task. Further, we found a fast heuristic algorithm to calculate the time-slot for each task, which is capable to reach a core utilization of 90% by considering typical industrial applications. Finally, experiments show the effectiveness of our heuristic and the performance in different settings.Publicad
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