DEADLINE CONSTRAINED MESSAGE SCHEDULING IN POINT-TO-POINT INTERCONNECTION
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Abstract:
A new message scheduling policy is proposed in this paper for delivering messages under deadline constraints. Unlike most existing work, this policy is intended for distributed systems with point-to-point interconnection topology. It is first shown that commonly used scheduling criteria like Earliest-Deadline-First do not work well in point-to-point interconnection topologies. Therefore, in the proposed policy, the scheduling of messages at each node is based on minimizing an estimate of the cost that the system will incur due to messages at that node missing their deadlines. The proposed policy can be implemented using an algorithm that has O(n) worst-case complexity, where n is number of messages waiting for transmission when a new message arrives. A modification that limits this worst-case complexity to O(B) where B is fixed constant is also proposed. Simulation results indicate that fewer messages miss their deadline in the proposed policy as compared to other policies. Index Terms--- Distributed real-time systems, point--to--point interconnection network, time-constrained communication, meshes, hypercubes.
