Scheduling analysis of fixed priority hard real-time systems with multiframe tasks
Areej Zuhily · White Rose eTheses Online (University of Leeds, The University of Sheffield, University of York) · 2009
Scheduling analysis of real time systems has been studied by most researchers assuming the tasks of the systems have constant worst case execution time bounds during their cycle of execution.However, this is not the case in a multiframe task where the execution time could be different from one instance to another, as in multimedia applications like MPEG.Some researchers have introduced sufficient scheduling analyses for a restricted model of multiframe tasks.The contributions in this thesis present scheduling analysis for a less strict model of multiframe tasks.The analysis is presented in two steps.In the first step, exact scheduling analysis is presented by response time analysis; where the worst case response time of multiframe tasks is formulated.This formulation is then extended to multiframe tasks that are subjected to blocking, release jitter and arbitrary deadlines.Another extension of the formulation is given to cover frame specific deadlines; where a multiframe task has more than one deadline relative to its frames.With large systems of multiframe tasks, the exact response time analysis becomes computationally intractable.So, in the second step we present and compare some sufficient approaches that analyze the schedulability of large systems with multiframe tasks.In this step we first study the safety of each approach then we compare them to find out the schedulability performance each of them provides.