Modern embedded platforms need sophisticated resource managers to utilize their heterogeneous computational resources efficiently. Furthermore, such platforms are subject to fluctuating workloads that are unforeseeable at design time. Predicting the incoming workload could enhance the efficiency of resource management in this situation. But is that the case? And, if so, how substantial is this improvement? Does multiple-step-ahead prediction of the workload contribute to this improvement? How precise must the prediction be to improve decisions rather than cause harm? By proposing a prediction-based resource manager that aims at meeting task deadlines while minimizing energy usage, and by conducting extensive tests, we attempt to provide answers to the aforementioned questions.