An Adaptive Fuzzy Scheduling and Fuzzy-PID Performance Control Model Suitable for Soft Real-time Systems

Abstract

In a soft real-time system, the deadline missing ratio is an important metric to evaluate system performance. In addition, considering the unsteadiness and unpredictability of a practical task running environment due to the unsteadiness of network communication and the estimation deviation, it is necessary to introduce fuzzy concept and theory to the scheduling and performance control of the soft real-time application systems oriented to communication and network fields. In this paper, a new adaptive soft real-time task scheduling model with the fuzzy-PID feedback controller was presented. In this model, we used the fuzzy scheduling algorithm in which the scheduling turn of a ready task is decided by the fuzzy inference result of its criticality degree and deadline distance. Meanwhile, in the adaptive control part, we used the fuzzy-PID controller that combined the fuzzy feedback controller and PID controller instead of traditional PID controller. The simulation test shows that our presented model can enable a soft real-time system with multi-level service characteristic reach steady state faster and has less miss ratio to its more important tasks.