Difference between Periodic and Sporadic Real-time Tasks
Prerequisite – Tasks in Real Time systems
1. Periodic Real-time Tasks :
The real-time task that is repeated after a certain time interval is known as periodic real-time task. Basically the periodic real-time tasks are controlled by the clock interrupts. Therefore, the periodic real-time tasks are also called clock-driven tasks.
For example, in a chemical plant temperatures, pressure and other attribute are measured periodically and all information is passed to controller.
2. Sporadic Real-time Tasks :
The real-time task that reoccurs at random instant is known as sporadic real-time task. Sporadic real-time task has some similarity to aperiodic real-time task but it is different from aperiodic real-time task. Basically all the high critical tasks are sporadic tasks.
For example, fire handling task in industry is sporadic task.
Difference between Periodic and Sporadic Real-time Tasks :
PERIODIC TASK | SPORADIC TASK |
---|---|
It reoccurs after a certain period of time. | It reoccurs at random instant. |
It is controlled by clock interrupts. | It is not controlled by clock interrupts. |
Time of occurrence of periodic tasks can be predicted. | Time of occurrence of sporadic tasks can’t be predicted. |
It includes moderate critical or low critical tasks. | It includes highly critical tasks. |
It includes normal system tasks. | It includes tasks that may lead to system failure. |
It can be easily scheduled by cyclic scheduler. | It is complex to schedule sporadic tasks by cyclic scheduler. |
Periodic tasks are allotted time frame in generalized task scheduler. | Sporadic tasks are allotted slack time in generalized task scheduler. |
Example: Measuring of temperature and pressure at a time interval. | Example: Emergency message arrivals in the system. |