/ COMPUTER-FUNDAMENTAL

FIFO scheduling algorithm

FIFO (first in first out) = FCFS (first come first served)

This algorithm is the most fair system.
The order of handling tasks depends on how fast they input.
If a task comes first, the task will be handled first.
This algorithm does not preempt the resources, which prevent starvation.
However, this system is not suitable for some specific tasks.

How FIFO works

IPC

Issue of FIFO

In the above pic, we can reduce waiting time.
If we put P1 at the end because P1 is the biggest burst time,
the order will be P2 -> P3 -> P1.
In this order, waiting time for P2: 0, P3: 3, P1: 6, and
Average waiting time is 3.

FIFO(= FCFS) is fair, but it is not effective for averaging waiting time.
It loses the user satisfy.

Convey effect

IPC Convey Effect is phenomenon associated with FCFS algorithm,
in which the entire OS slows down due to few slow processes.