Real time system has well defined fixed time constraints. Processing should be done within the Defined constraints. A primary objective of real-time systems is to provide quick event response time and thus meet the scheduling deadlines. User convenience and resource utilization are of secondary concern to real-time system designers. In Real time systems, processor is allocated to the highest priority process among those that are ready to execute. Higher priority processes preempt execution of the lower priority processes. This form is called as ‘priority–based preemptive scheduling’.
The primary functions of the real time operating system are to:
Manage the processor and other system resources to meet the requirements of an application.
Synchronize with and respond to the system events.
Move the data efficiently among processes and to perform coordination among these processes.
Types of real time system:
1. Hard Real Time: - Hard real time means strict about adherence to each task deadline. When an event occurs, it should be serviced within the predictable time at all times in a given hard real time system.
Example: Video Transmission, each picture frame and audio must be transferred at fixed rate.
2. Soft Real Time: Soft real time means that only the precedence and sequence for the task operations are defined, interrupt latencies and context switching latencies are small. There can be few deviations between expected latencies of the tasks and observed time constraints and a few deadline misses are accepted.
Example: Mobile phone, Digital Cameras and orchestra playing robots.
0 Comments