Difference between Periodic and Aperiodic Real-time Tasks

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. The time interval after which the task repeats itself is known as period of the task.

For example, when a flight is detected by the radar and until the radar exists, the radar signal zone is an example of periodic real-time task.

2. Aperiodic real-time Tasks :
The real-time task that occurs at any random time is known as aperiodic real-time task. Between two aperiodic real-time tasks the time interval may be even zero. Soft real-time tasks are generally aperiodic real-time tasks. It is also possible that these tasks may occur frequently or there might be a large time interval between two aperiodic real-time tasks.

For example, typing on the key-board is an aperiodic real-time task.

Difference between Periodic and Aperiodic Real-time Tasks:

It repeats itself after a certain time interval. It can occur at random instants.
These tasks are controlled by clock interrupts. These tasks are not controlled by clock interrupts.
The time interval between occurrence of two consecutive tasks can’t be zero. The time interval between occurrence of two consecutive tasks can be zero.
Periodic tasks generally include soft and hard real-time tasks both. Aperodic tasks generally include soft real-time tasks.
Deadline of all instances of periodic task can be meet easily. To meet deadline of all instances of an aperodic task is quite difficult.
It includes vast majority of internal tasks. It includes interactive task with users.
Example: Taking information from sensor at a time interval. Example: Logging task in a distributed system.

Attention reader! Don’t stop learning now. Get hold of all the important CS Theory concepts for SDE interviews with the CS Theory Course at a student-friendly price and become industry ready.

My Personal Notes arrow_drop_up

Check out this Author's contributed articles.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.