A Stretching Algorithm for Parallel Real-time DAG Tasks on Multiprocessor SystemsReport as inadecuate

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1 LIGM - Laboratoire d-Informatique Gaspard-Monge 2 LISSI - Laboratoire Images, Signaux et Systèmes Intelligents

Abstract : Parallelism is becoming more important nowadays due to the increasing use of multiprocessor systems. In this paper, we study the problem of scheduling periodic parallel real-time Directed Acyclic graph DAG tasks on m homogeneous multiprocessor systems. A DAG task is an example of inter-subtask parallelism. It consists of a collection of dependent subtasks under precedence constraints. The dependencies between subtasks make scheduling process more challenging. We propose a stretching algorithm applied on each DAG tasks to transform them into a set of independent sequential threads with intermediate offsets and deadlines. The threads obtained with the transformation are two types, i fully-stretched master threads with utilization equal to 1 and ii constrained-deadline independent threads. The fully-stretched master threads are assigned to dedicated processors and the remaining processors m- ≤ m, are scheduled using global EDF scheduling algorithm. Then, we prove that preemptive global EDF scheduling of stretched threads has a resource augmentation bound equal to 3+ √ 5-2 for all tasksets with n < ϕ * m , where n is the number of tasks in the taskset and ϕ is the golden ratio 1 .

Keywords : Real-time scheduling parallel tasks Directed Acyclic Graphs global EDF scheduling speedup factor

Author: Manar Qamhieh - Laurent George - Serge Midonnet -

Source: https://hal.archives-ouvertes.fr/


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