Flexible Maximum Urgency First Scheduling for Distributed Real-Time Systems
Yingming Chen · 2006
In the rest of this report, we first describe the design of the FMUF scheduling strategy. Then, we present simulation results to demonstrate that FMUF can provide performance isolation for mission-critical tasks. 2 FMUF Scheduling The following are some definitions for FMUF Scheduling strategy:-Two types of tasks: mission-critical tasks and best effort tasks,categorized by its importance specified by users.-All real-time priorities are divided into two classes: a high priority class and a low priority class. A task whose priority is in the high priority class is in the high group. The other tasks are in the low group. That is, a task in the high group always has a higher priority than any tasks in the low group. Inside each group, all tasks are ordered by their end-to-end deadline, and end-to-end Deadline Monotonic scheduling algorithm is applied to assign subpriorities. The basic idea of FMUF is to utilize an adaptive mechanism to dynamically adjust the priority of best effort tasks (i.e., move some best effort tasks into or out of the high group) according to the current conditions at runtime. In the rest of this section, we present two approaches to implement this strategy.