Departmental Papers (CIS)

Date of this Version

4-2014

Document Type

Conference Paper

Comments

20th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS 2014), Berlin, Germany, April 2014.

Abstract

Real-time systems are becoming increasingly complex. A modern car, for example, requires a multitude of control tasks, such as braking, active suspension, and collision avoidance. These tasks not only exhibit different degrees of safety criticality but also change their criticalities as the driving mode changes. For instance, the suspension task is a critical part of the stability of the car at high speed, but it is only a comfort feature at low speed. Therefore, it is crucial to ensure timing guarantees for the system with respect to the tasks’ criticalities, not only within each mode but also during mode changes.

This paper presents a partitioned multi-processor scheduling scheme for multi-modal mixed-criticality real-time systems. Our scheme consists of a packing algorithm and a scheduling algorithm for each processor that take into account both mode changes and criticalities. The packing algorithm maximizes the schedulable utilization across modes using the sustained criticality of each task, which captures the overall criticality of the task across modes. The scheduling algorithm combines Rate-Monotonic scheduling with a mode transition enforcement mechanism that relies on the transitional zero-slack instants of tasks to control low-criticality tasks during mode changes, so as to preserve the schedulability of high-criticality tasks. We also present an implementation of our scheduler in the Linux operating system, as well as an experimental evaluation to illustrate its practicality. Our evaluation shows that our scheme can provide close to twice as much tolerance to overloads (ductility) compared to a mode-agnostic scheme.

Subject Area

CPS Real-Time

Publication Source

20th IEEE Real-Time and Embedded Technology and Applications Symposium (RTAS 2014)

DOI

10.1109/RTAS.2014.6925995

Copyright/Permission Statement

© 2014 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.

Share

COinS
 

Date Posted: 16 October 2015

This document has been peer reviewed.