All CPU Scheduling Algorithms in Operating System

Welcome to a comprehensive exploration of All CPU Scheduling Algorithms in the operating system. In this article, we’ll delve into the various scheduling algorithms used in operating systems, shedding light on their functions, advantages, and limitations. By the end of this journey, you’ll have a deep understanding of how these algorithms manage the allocation of CPU time to different processes.


CPU scheduling is a crucial aspect of operating system design, as it directly impacts a system’s efficiency and responsiveness. It plays a pivotal role in ensuring that multiple processes run smoothly on a single CPU, optimizing resource utilization. In this article, we will demystify All CPU Scheduling Algorithms and provide valuable insights into their working mechanisms.

First-Come, First-Served (FCFS)

The First-Come, First-Served (FCFS) scheduling algorithm is as simple as its name suggests. It allocates the CPU to the first process that arrives, and each process is served in the order it enters the queue. While this approach seems fair, it can lead to long waiting times for processes with shorter burst times.

Shortest Job First (SJF)

The Shortest Job First (SJF) algorithm aims to minimize waiting times by selecting the process with the shortest burst time. This approach ensures that smaller tasks are completed first, reducing overall response times. However, predicting the exact burst time of processes can be challenging.

Priority Scheduling

Priority Scheduling assigns priorities to each process, and the CPU is allocated to the highest-priority task. This approach allows for the execution of critical tasks before others, but it can lead to starvation, where low-priority processes are never executed.

Round Robin (RR)

Round Robin (RR) is a widely used algorithm that allocates time slices to each process in a circular manner. This method ensures fairness and prevents any single process from hogging the CPU. However, it may not be suitable for time-sensitive tasks.

Multilevel Queue Scheduling

Multilevel Queue Scheduling divides processes into multiple queues based on priority. Each queue may use its own scheduling algorithm, allowing for a flexible approach in managing processes of different priorities. This is particularly useful in multitasking environments.

Multilevel Feedback Queue Scheduling

Multilevel Feedback Queue Scheduling extends the multilevel queue concept by allowing processes to move between queues dynamically. This approach is highly adaptive and well-suited for systems with varying workloads.

Lottery Scheduling

Lottery Scheduling allocates tickets to processes, and the CPU is awarded through a lottery system. The more tickets a process has, the higher its chances of winning the CPU lottery. This method introduces an element of randomness into scheduling.


What is CPU scheduling in an operating system?

CPU scheduling is a technique used by operating systems to manage and allocate CPU resources to various processes running on a system.

Why is CPU scheduling important?

CPU scheduling ensures efficient resource utilization, fairness, and responsiveness in a multi-tasking environment, making it a fundamental aspect of operating system design.

What are the common scheduling algorithms used in operating systems?

Some common scheduling algorithms include First-Come, First-Served, Shortest Job First, Priority Scheduling, Round Robin, Multilevel Queue Scheduling, and Multilevel Feedback Queue Scheduling.

How does Round Robin scheduling work?

Round Robin scheduling allocates a fixed time slice to each process in a circular manner, ensuring fairness and preventing any single process from monopolizing the CPU.

What are the advantages of Priority Scheduling?

Priority Scheduling allows for the execution of high-priority tasks first, making it suitable for time-sensitive operations.

What are the drawbacks of the First-Come, First-Served (FCFS) algorithm?

FCFS can lead to long waiting times for processes with shorter burst times, potentially causing inefficiency.


In conclusion, understanding CPU scheduling algorithms is crucial for optimizing the performance and responsiveness of an operating system. Each algorithm has its strengths and weaknesses, and the choice of the right one depends on the system’s requirements. By exploring the All CPU Scheduling Algorithms in the operating system, you gain valuable insights into the core of modern computing.


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