Integrated scheduling of tasks and messages in distributed real-time systems

  • Authors:

  • G. Manimaran;Shashidhar Merugu;Anand Manikutty;C. Siva Ram Murthy

  • Affiliations:

  • Dept. of Computer Science and Engineering, Indian Institute of Technology Madras, Chennai;College of Computing, Georgia Institute of Technology Atlanta, GA;Dept. of Computer Sciences, University of Wisconsin Madison, WI;Dept. of Computer Science and Engineering, Indian Institute of Technology Madras, Chennai

  • Venue:
  • Engineering of distributed control systems
  • Year:
  • 2001

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Abstract

The demand for more and more complex real-time applications which require high computational needs with timing constraints, and geographical distribution of computational entities (tasks) of these applications, have led to the choice of distributed systems as a natural candidate for supporting such real-time applications, due to their potential for high performance and reliability. The distributed real-time system considered here consists of uniprocessor or multiprocessor nodes connected through a multihop network. Scheduling of tasks in such a system involves scheduling of dynamically arriving tasks within a node (local scheduling), migration of tasks across the network (global scheduling) if it is not possible to schedule them locally, and (iii) scheduling of messages on communication links (message scheduling) to support inter-task communication and task migration. Most of the existing schemes on scheduling in distributed real-time systems have addressed each of these issues in isolation. Moreover, these schemes consider the load on the processors at a node as the basis to migrate tasks from a heavily loaded node (sender) to a lightly loaded node (receiver). We believe that the identification of a receiver node should be based not only on the load on its processors, but also on the availability of a path, which satisfies the bandwidth required for the task migration, from the sender to that receiver. In this paper, we present an integrated framework for scheduling dynamically arriving real-time tasks in distributed real-time systems. Our proposal consists of (i) algorithms for global scheduling and (ii) interactions among the three schedulers in a way to improve the schedulability of the system. The effectiveness of the proposed framework has been evaluated through simulation by comparing it with existing schemes.