What is CPU Scheduling?

CPU Scheduling is a process of determining which process will own CPU for execution while another process is on hold. The main task of CPU scheduling is to make sure that whenever the CPU remains idle, the OS at least select one of the processes available in the ready queue for execution. The selection process will be carried out by the CPU scheduler. It selects one of the processes in memory that are ready for execution.

Types of CPU Scheduling Algorithms-

1. Preemptive - Preemptive scheduling is used when a process switches from running state to ready state or from the waiting state to the ready state.

2. Non-preemptive - Non-Preemptive scheduling is used when a process terminates , or when a process switches from running state to waiting state.

SJF- Shortest Job First

Criteria - Burst Time

Shortest job first (SJF) is a scheduling process that selects the waiting process with the smallest execution time to execute next. This scheduling method may or may not be preemptive. Significantly reduces the average waiting time for other processes waiting to be executed.

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SRTF- Shortest Remaining Time First

Criteria - Burst Time

Shortest Remaining Time First (SRTF) is the preemptive version of Shortest Job Next (SJN) algorithm, where the processor is allocated to the job closest to completion. In SRTF the process with the smallest amount of time remaining until completion is selected to execute.

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RR- Round Robin

Criteria -Time Quantum

The name of this algorithm comes from the round-robin principle, where each person gets an equal share of something in turn. It is mostly used for scheduling algorithms in multitasking. This algorithm method helps for starvation free execution of processes.

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