Real-Time Computing
External
- https://en.wikipedia.org/wiki/Real-time_computing
- Real-Time Computing: A New Discipline of Computer Science and Engineering https://kabru.eecs.umich.edu/papers/publications/1994/ramanathan-shin-ieee-proceedings.pdf
Internal
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. The usefulness of a result is zero after its deadline.
- Soft Real-time System - the usefulness of a result degrades after its deadline, degrading 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.