The incorporation of unbounded components (i,e. software modules that cannot be analysed to produce realistic worst case execution times) into hard real-time applications has been recognized as a key issue for the nex...
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The incorporation of unbounded components (i,e. software modules that cannot be analysed to produce realistic worst case execution times) into hard real-time applications has been recognized as a key issue for the next generation of systems. We present a system model that caters for the three main approaches to integrating unbounded components - imprecise computation, sieve functions and multiple versions. This model is feasible because it is supported by schedulability tests that will guarantee the bounded tasks. These tests are defined in the paper. A simple computational model thal uses preemptive priority-based dispatching is required. The widespread use of techniques such as imprecise computation will only happen if they are integrated into standard software engineering methods. We therefore show how the techniques can be realized in Ada 9X.
In this study, we propose an object-based multimedia model for specifying the QoS (quality of service) requirements, such as the maximum data-dropping rate or the maximum data-delay rate. We also present a resource al...
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In this study, we propose an object-based multimedia model for specifying the QoS (quality of service) requirements, such as the maximum data-dropping rate or the maximum data-delay rate. We also present a resource allocation model, called the net-profit model, in which the satisfaction of user's QoS requirements is measured by the benefit earned by the system. Based on the net-profit model, the system is rewarded if it can allocate enough resources to a multimedia delivery request and fulfill the QoS requirements specified by the user. At the same time, the system is penalized if it cannot allocate enough resources to a multimedia delivery request. We first investigate the problem of how to allocate resources efficiently, so that the QoS satisfaction is maximized. However, the net-profit may be distributed unevenly among the multimedia delivery requests. Thus, the second problem discusses how to allocate the resource efficiently so that the net-profit difference is minimized between any two multimedia requests. A dynamic programming based algorithm is proposed to find such an optimal solution with the minimum net-profit differences.
Real-time systems are now of critical importance to many real-world applications. Consequently, there is now increased interest in tools which specifically support the development of software for real-time systems. Wh...
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Real-time systems are now of critical importance to many real-world applications. Consequently, there is now increased interest in tools which specifically support the development of software for real-time systems. While much progress has been made in recent years in providing general purpose programming support by means of sophisticated software development environments, much of the construction of real-time systems is still performed with comparatively primitive programming languages and support tools. Furthermore, most existing high-level programming languages to date have provided, at, best, limited support for programming real-time applications. File programming language GARTL has been designed, dedicated to supporting the development of hard real-time systems using the paradigm of imprecise computation and the notion of multi-version tasks. This paper focuses on the development enviornment assoicated with GARTL, known as GARTEN. In particular, we describe GARTAAN, a component of GARTEN, which attempts to automate the most costly stage of real-time software development, that of testing and debugging. The principal function of GARTAAN is to perform timing analysis of GARTL code, necessary to ensure that the hard real-time systems produced operate within their timing constraints.
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