Joint offloading and scheduling decisions for DAG applications in mobile edge computing

Mobile edge computing (MEC) is a promising technology to support computation-intensive tasks for mobile devices which are usually associated with limited resources. Many researches from both scientific and industrial field have put focuses on MEC. However, most of them assume that in a MEC environment, the offloaded tasks are independent or that there is only one server in the MEC center. Nevertheless, in reality, tasks with dependencies take the majority and in a MEC center, there are usually multiple servers. Under this circumstance, previous methods no longer take effects. In this work, we consider offloading with precedence constraints among tasks, and try to minimize makespan over a MEC center with multiple servers. This problem becomes more complex given that a task can not start unless its predecessors are completed. To solve the problem, we jointly involve front end task offloading order and back end scheduling to optimize makespan, and propose a corresponding algorithm called joint re-ordering and frequency scaling (JRFS). Extensive experiments have been conducted. The results show that compared with several other methods, JRFS can achieve better makespan. (c) 2019 Elsevier B.V. All rights reserved.