A Beginner’s Guide to Process Scheduling Algorithms

A Process Scheduling Algorithm is the ruleset an operating system uses to decide which program gets to use the CPU and for how long. Because a CPU can only execute one task at a time, the operating system (OS) needs an efficient manager to juggle multiple running applications without crashing or freezing. Core Performance Metrics

To determine if a scheduling algorithm is effective, computer scientists evaluate it using a few standard performance criteria:

Arrival Time (AT): The exact moment a process enters the “ready queue” waiting room.

Burst Time (BT): The total execution time the process actually needs from the CPU.

Waiting Time (WT): The total time a process spends sitting passively in the ready queue.

Turnaround Time (TAT): The total lifespan of the process from arrival to completion. Formula: Preemptive vs. Non-Preemptive Scheduling

Every scheduling algorithm falls into one of two fundamental execution styles: