A Metric for Quantifying Similarity between Timing Constraint Sets in Real-Time Systems

Abstract

Real-time systems are systems in which their timing behaviors must satisfy a specified set of timing constraints and they often operate in a real-world environment with scarce resources. As a result, the actual runtime performance of these systems may deviate from the design, either inevitably due to unpredictable factors or by intention in order to improve system’s other Quality-of-Service (QoS) properties. In this article, we first introduce a new metric, timing constraint set similarity , to quantify the resemblance between two different timing constraint sets. Because directly calculating the exact value of the metric involves calculating the size of a polytope which is a # P -hard problem, we instead introduce an efficient method for estimating its bound. We further illustrate how this metric can be exploited for improving system predictability and for evaluating trade-offs between timing constraint compromises and the system’s other QoS property gains.