Algorithm:
- Processes are added to a queue in order of arrival
- Picks the first process in the queue and executes it
- If the process needs more time to complete it is placed at the end of the queue Details:
- Simple to implement
- However, average waiting time can be quite high
Abstract
Given the following table:
Calculate the:
- Completion Time
- Turn Around Time
- Waiting Time
Example
First we can work through and create a relative time graph: At:
- t=0 The only ready process is P2, so we run P2 until completion
- t=1 P2 is now finished, but nothing else is ready
- t=2 P1 and P3 have now arrived, P1 will get priority here just by the way we have defined them. P1 runs until completion
- t=4 P1 is now finished, in the mean time P4 has arrived, but P3 takes priority and is run until completion
- t=7 P3 is now finished, we can run P4 until completion
- t=12 P4 is now finished
From this we can extend our table as such:
