Question

Suppose there are three processes, namely PA, PB, PC. How does the CPU switch between these processes? Discuss and draw the diagram for this.

A) Round Robin
B) First Come First Serve
C) Priority Scheduling
D) Shortest Job Next

Answer 1

The CPU uses various scheduling algorithms such as Round Robin, First Come First Serve, Priority Scheduling, and Shortest Job Next to switch between processes like PA, PB, and PC.

Step-by-step explanation:

The CPU switches between different processes using scheduling algorithms that dictate the order and the time a process is allowed to use the CPU. There are various scheduling algorithms, each with its own way of determining which process should run next:

Round Robin (RR)

In Round Robin scheduling, each process is assigned a fixed time slot or quantum. The processes are placed in a queue in a circular fashion. When a process's time quantum expires, the next process in the queue gets the CPU. This continues in a clockwise sequence, ensuring that all the processes get an equal share of the CPU time.

First Come First Serve (FCFS)

First Come First Serve is the simplest scheduling algorithm. Processes are queued in the order they arrive. The CPU serves the first process in the queue completely before moving to the next one.

Priority Scheduling

In Priority Scheduling, each process is assigned a priority. The process with the highest priority (or lowest numerical value assuming 1 is high) is selected next. If two processes have the same priority, FCFS rules apply. There is a version where priorities may dynamically change to prevent starvation, known as aging.

Shortest Job Next (SJN)

In the Shortest Job Next (also known as Shortest Job First) algorithm, the CPU selects the process that has the smallest execution time remaining. This minimizes average waiting time for processes.