Dynamic Real-Time Task Scheduling on Hypercubes

Prasant Mohapatra

Abstract: Multiprocesssor systems have emerged as an important computing means for real-time applications and have received increasing attention. However, until now, little research has been done on the problem of on-line scheduling of parallel tasks with deadlines in partitionable multiprocessor systems. Meshes and hypercubes belong to this class of multiprocessors. In this paper, we propose a new on-line scheduling algorithm for hypercube systems called Deferred Earliest Deadline First (DEDF). The main idea of the DEDF algorithm is to defer the scheduling as long as possible, so that a set of jobs is scheduled at once instead of one at a time. For processor allocation using DEDF, we have introduced a new concept—available time window (ATW). By using ATW, the system utilization can be improved and thereby the deadlines of more of tasks can be met. Simulation results indicate that the DEDF algorithm performs significantly better than the earlier proposed Buddy/RT and Stacking algorithms for a wide range of workloads.