Subtask Deadline Assignment for Complex Distributed Soft Real-Time Tasks

Abstract

Complex distributed tasks often involve parallel execution of subtasks at different nodes. To meet the deadline of a global task, all of its parallel subtasks have to be finished on time. Comparing to a local task (which involves execution at only one noa global task may have a much harder time making its deadline because it is fairly likely that at least one of its subtasks run into an overloaded node. Another problem with complex distributed tasks occurs when a global task consists of a number of serially executing subtasks. In this case, we have the problem of dividing up the end-to-end deadline of the global task and assigning them to the intermediate subtasks. In this paper, we study both of these problems. Different algorithms for assigning deadlines to subtasks are presented and evaluated. Keywords: soft real-time, distributed systems, parallel systems, deadline assignment, scheduling.