Talks and Poster Presentations (with Proceedings-Entry):
R Dobrin, G. Fohler, P. Puschner:
"Translating Offline Schedules into Task Attributes for Fixed Priority Scheduling";
Talk: IEEE Real-Time Systems Symposium,
London, United Kingdom;
- 2001-12-06; in: "Proceedings of the 22nd IEEE Real-Time Systems Symposium",
Offline scheduling and fixed priority scheduling (FPS) are often considered as complementing and incompatible paradigms. A number of industrial applications demand temporal properties (predictability, jitter constraints, end toend deadlines, etc.) that are typically achieved by using offline scheduling. The rigid offline scheduling schemes used, however, do not provide for flexibility. FPS has been widely studied and used in a number of applications, mostly due to its simple runtime scheduling, and small overhead. It can provide more flexibility, but is limited with respect to predictability, as actual start and completion times of exe cution depend on runtime events. In this paper we show how offline scheduling and FPS runtime scheduling can be combined to get the advantages of both -- the capability to cope with complex timing con straints and flexibility. The paper assumes that a schedule for a set of tasks with complex constraints has been con structed offline. It presents a method to analyze the offline schedule and derive an FPS task set with FPS attributes priority, offset, and period, such that the runtime FPS exe cution matches the offline schedule. It does so by analyzing the schedule and setting up inequality relations for the pri orities of the tasks under FPS. Integer linear programming (ILP) is then used to find a FPS priority assignment that ful fils the relations. In case the priority relations for the tasks of the offline schedule are not solvable we split tasks into the number of instances, to obtain a new task set with con sistent task attributes. Our schedule translation algorithm keeps the number of newly generated artifact tasks minimal.
Electronic version of the publication:
Created from the Publication Database of the Vienna University of Technology.