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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
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
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
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
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.
- Spring '14