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Programming Embedded Systems, 2nd Edition
book

Programming Embedded Systems, 2nd Edition

by Michael Barr, Anthony Massa
October 2006
Intermediate to advanced content levelIntermediate to advanced
336 pages
9h 13m
English
O'Reilly Media, Inc.
Content preview from Programming Embedded Systems, 2nd Edition

Real-Time Characteristics

Engineers often use the term real-time to describe computing problems for which a late answer is as bad as a wrong one. These problems are said to have deadlines, and embedded systems frequently operate under such constraints. For example, if the embedded software that controls your antilock brakes misses one of its deadlines, you might find yourself in an accident. So it is extremely important that the designers of real-time embedded systems know everything they can about the behavior and performance of their hardware and software. In this section, we will discuss the performance characteristics of real-time operating systems.

The designers of real-time systems spend a large amount of their time worrying about worst-case performance. They must constantly ask themselves questions such as: what is the worst-case amount of time between the moment a human operator presses the brake pedal and the moment an interrupt signal arrives at the processor? What is the worst-case interrupt latency? And what is the worst-case amount of time for the software to respond by triggering the braking mechanism? Average or expected-case analysis simply will not suffice in such systems.

Most of the real-time operating systems available today are designed for possible inclusion in real-time systems. Ideally, their worst-case performance is well understood and documented. To earn the distinctive title of “real-time operating system,” an operating system should be deterministic ...

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Publisher Resources

ISBN: 0596009836Supplemental ContentErrata Page