Abstract
In the design phase of real-time systems, it cannot be expected that the timing attributes of all tasks are completely specified and never changed. The increased computation times or shortened periods in a schedulable system often cause deadlines to be missed. In such situations, sensitivity analysis is an effective approach to provide quantitative indications for the design modification, by identifying the borderlines on parameter variations while keeping the systems schedulable. In this paper, we propose a new approach to analyze the sensitivity of the timing parameters of tasks with strict periods in multi-core real-time systems. We first analyze a schedulability condition to determine whether a task is schedulable on a given processor without changing the start times of the existing tasks. Then, following a game theory analogy, we design recursive algorithms to compute the permissible changes in the task timing parameters, by allowing each task to optimize its own start time and processor allocation. Finally, we conduct experiments with randomly generated tasks to show that our approach is more efficient than the existing solutions to solve the sensitivity problem. The proposed approach has a wide range of applications, only guiding the design of multi-core systems, but also improving the robustness of a design subject to future changes.
Highlights
Scheduling and schedulability analysis for real-time systems have been a fundamental issue in providing guarantees for temporal feasibility of task execution in anticipated situations
PREVIOUS RESULTS ON SCHEDULABILITY ANALYSIS FOR STRICTLY PERIODIC TASKS Schedulability analysis which determines whether a set of tasks with temporal parameters meets their constraints according to a given scheduling algorithm, can significantly increase the efficiency of design of real-time systems, and is a critical foundation for sensitivity analysis
The schedulability condition proposed provides a constraint on the computation time and period of a single task when it is schedulable with other tasks, and will be adopted to analyze the parameter variations of strictly periodic tasks in later sections
Summary
Scheduling and schedulability analysis for real-time systems have been a fundamental issue in providing guarantees for temporal feasibility of task execution in anticipated situations. We first analyze a schedulability condition to determine whether strictly periodic tasks are schedulable in a multi-core real-time systems, propose approaches to seek affordable changes in the task timing parameters before the system becomes unschedulable. B. CONTRIBUTIONS In this paper, we study the sensitivity problem for tasks with strict periods and propose a new approach to compute the admissible changes in the timing parameters upon a multicore real-time platform. This condition works no matter how many tasks have already been assigned to a specific processor, and does not require any form of search It is efficient and provides a schedulability constraint for the computation time and period of a single task when all existing tasks are fixed. IX presents the conclusions of this paper and the directions for future work
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