Controlled Duplication Scheduling of Real-Time Precedence Tasks on Heterogeneous Multiprocessors

Duplication based heuristics have been widely utilized for scheduling communication intensive, precedence constrained tasks on multiple processors. Duplicating the predecessor of a task on the processor to which the task is assigned can result in the minimization of the communication cost. This helps in reducing the schedule length. However, this reduction comes at the cost of extra computing power required to duplicate the tasks. We have tried to address this trade-off in this paper. We propose “controlled” duplication algorithms for scheduling real-time periodic tasks with end-to-end deadlines on heterogeneous multiprocessors. We observe that whether to duplicate tasks or not is decided by the task deadlines. In the case that the deadline can be met without duplication, more schedule holes are created. These holes can be used to schedule other tasks. Simulations show that the proposed algorithms efficiently utilize the holes and improve the success ratio by 15%− 50% versus comparable algorithms.