First In, First Out (FIFO)

The most basic algorithm we can implement is known as First In, First Out (FIFO) scheduling or sometimes First Come, First Served (FCFS).

FIFO has a number of positive properties: it is clearly simple and thus easy to implement. And, given our assumptions, it works pretty well.

Example of FIFO

Let’s do a quick example together. Imagine three jobs arrive in the system, A, B, and C, at roughly the same time ($T$_$arrival$ = 0). Because FIFO has to put some job first, let’s assume that while they all arrived simultaneously, A arrived just a hair before B which arrived just a hair before C. Assume also that each job runs for 10 seconds. What will the average turnaround time be for these jobs?