Real-Time Computing: Difference between revisions
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Formally, a system is said of be real-time if the correctness of an operation depends not only upon its logical correctness, but also upon the time in which the operation is performed. Real-time systems are classified by the consequences of missing a deadline: | Formally, a system is said of be real-time if the correctness of an operation depends not only upon its logical correctness, but also upon the time in which the operation is performed. Real-time systems are classified by the consequences of missing a deadline: | ||
* '''Hard''' Real-Time System - missing a deadline is a total system failure. | * <span id='Hard'></span>'''Hard''' Real-Time System - missing a deadline is a total system failure. | ||
* '''Firm''' Real-Time System - infrequent deadline misses are tolerable, but may degrade the system's quality of service. | * <span id='Firm'></span>'''Firm''' Real-Time System - infrequent deadline misses are tolerable, but may degrade the system's quality of service. | ||
=Real-time Operating System= | =Real-time Operating System= | ||
Revision as of 00:46, 19 April 2018
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Overview
A real-time system is subject to a "real-time constraint" - a guaranteed response within a specified time constraint between event to system response. Real-time systems control an environment by receiving data, processing it, and returning the results sufficiently quickly to affect the environment at that time.
Formally, a system is said of be real-time if the correctness of an operation depends not only upon its logical correctness, but also upon the time in which the operation is performed. Real-time systems are classified by the consequences of missing a deadline:
- Hard Real-Time System - missing a deadline is a total system failure.
- Firm Real-Time System - infrequent deadline misses are tolerable, but may degrade the system's quality of service.
Real-time Operating System
An operating system intended to serve real-time applications that process data as it comes, without buffer delays. The system attempts to insure the guaranteed response time, possibly at the expense of the throughput.
Real-time Constraint
A real-time constraint is a guaranteed response within a specified time constraint between event to system response. Real-time constraints are also referred to as "deadlines". Deadlines must always be met, regardless of system load. For hard and firm real-time systems, the usefulness of a result is zero after its deadline.