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Title Design and Implementation of a Simulator for Measuring the Quality of Service for Distributed Multimedia Applications
Author Kristensen, Rolf Esbjørn
Supervisor Pop, Paul (Embedded Systems Engineering, Department of Informatics and Mathematical Modeling, Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark)
Institution Technical University of Denmark, DTU, DK-2800 Kgs. Lyngby, Denmark
Thesis level Master's thesis
Year 2009
Abstract Multimedia applications have become widespread today, from streaming over the Internet to portable music and video players. Increasingly multimedia applications are implemented using embedded architectures, which have very tight constraints in terms of cost, performance, power consumption, size, etc. Examples of such systems are smart-phones, an iPod or a TV set-top-box. Designing embedded systems implementing multimedia applications is difficult because of the inherent variability of functionality execution times (which depend on the video or audio streams processed, their resolution, frame rate, etc.) and stringent Quality-of-Service (QoS) requirements on their performance (e.g., a playback of 25 frames per second for a video device). Real-time systems theory provides analysis methods that can determine if an application implemented on an embedded architecture meets its timing constraints. There are a lot of results for hard real-time systems, which have to meet their deadlines even in the worst-case, otherwise something catastrophic can happen. In contrast, a multimedia application is a soft real-time system, where certain degradation of performance can be accepted, provided it is not below a given level of QoS. Multimedia systems are difficult to analyse using existing schedulability analysis theory. Designing an architecture based on the worst-case leads to over design: too much computing power, which is seldom used. Hence, the focus of this thesis is to implement a simulator that can support the designer in evaluating very early in the development process several embedded architecture implementations, and deciding which one meets the QoS requirements for a given multimedia application. This can reduce the time-to-market and development costs by avoiding building a physical prototype, which is costly and time-consuming. Besides evaluating hardware architectures (CPUs, dedicated hardware, buses), we are also interested in using the simulator to evaluate several scheduling policies, which have a strong impact on the behaviour of the application. Our simulator, which is based on the SystemC library, can take into account Fixed-Priority preemptive scheduling (FP), Earliest Deadline First scheduling (EDF), the Linux 2.6 scheduler and Constant-Bandwidth Server scheduling (CBS). The idea of the CBS is to divide a resource (CPU or bus) into virtual resources, which are given a certain budget. This is especially useful if several applications (both hard and soft real-time) have to share the same architecture. The simulator has been used to evaluate several architecture alternatives for a settop- box application, using different hardware components and scheduling policies. As the experiments show, using the simulator we can choose very quickly the right architecture and scheduling policy. The simulator can also help in deciding the scheduling parameters, such as the bandwidth for the CBS servers.
Imprint Technical University of Denmark (DTU) : Kgs. Lyngby, Denmark
Series IMM-M.Sc.-2009-16
Original PDF ep09_16.pdf (4.23 MB)
Admin Creation date: 2009-03-31    Update date: 2010-10-28    Source: dtu    ID: 240849    Original MXD