What are different types of CPU scheduling and the scheduling criteria?

Process scheduler assigns different processes to CPU based on particular scheduling algorithms.

The scheduling is responsible for taking part in the scheduling process that is the set of the policies and mechanisms to control the order in which the jobs can be completed. By using the scheduling algorithms the scheduler is done.

Types of Process Scheduling Algorithms

The different types of process scheduling algorithms are as follows −

• FCFS(First Come First Serve)

• SJF or shortest job next.

• Round Robin.

• Shortest Remaining time.

• Priority Scheduling.

• Multiple level queues.

The scheduling criterion is responsible for helping in the design of the good scheduler. These criteria are as follows −

CPU Utilization

The scheduling algorithm should be designed in such a way that the usage of the CPU should be as efficient as possible.

Throughput

It can be defined as the number of processes executed by the CPU in a given amount of time. It is used to find the efficiency of a CPU.

Response Time

The Response time is the time taken to start the job when the job enters the queues so that the scheduler should be able to minimize the response time.

Response time = Time at which the process gets the CPU for the first time - Arrival time

Turnaround time

Turnaround time is the total amount of time spent by the process from coming in the ready state for the first time to its completion.

Turnaround time = Burst time + Waiting time

or

Turnaround time = Exit time - Arrival time

Waiting time

The Waiting time is nothing but where there are many jobs that are competing for the execution, so that the Waiting time should be minimized.

Waiting time = Turnaround time - Burst time

Fairness

For schedulers there should be fairness for making sure that the processes get the fair share of chances to be executed.