That is a distributed computing system is a

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Unformatted text preview: means that the application produces correct results when its processing completes. However, in real life, we often come across situations in which it is not only sufficient to obtain correct results, but the results must be produced within some specified time frame (deadline) to be useful. A few examples of such applications are: 1. An aircraft must process accelerometer data within a certain period (say every 20 milliseconds) that depends on the specifications of the aircraft. Failure to do so could cause the aircraft to go away from its right course or may even cause it to crash. 2. Failure to respond in time to an error condition in a nuclear reactor thermal power plant could result in a melt-down. 3. Failure to respond in time to an error condition in the assembly line of an automated factory could result in several product units that will have to be ultimately discarded. 4. A request for booking a ticket in a computerized railway reservation system must be processed within the passenger's perception of a reasonable time (say 3 minutes). Systems that are designed for processing such applications are called real-time systems. That is, a real-time system is a system that must satisfy the requirement of producing the desired results before a certain deadline. If it delivers the correct result, but after the deadline, the system is regarded as having failed. Thus timely production of the result of processing is as important as its correctness in a realtime system. Operating systems that are designed to handle the processing requirements of realtime systems are called real-time operating systems. The goals of CPU scheduling in traditional timesharing computer systems are optimal throughput, optimal resource utilization, and fairness. In contrast, the main goal of CPU scheduling in real-time systems is to allow as many time-critical processes as possible to be processed in time to meet their deadlines. Network and Distributed Operating Systems Over the past few decades, advancements in microelectronic technology have resulted in the availability of fast, inexpensive comput...
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This document was uploaded on 04/07/2014.

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