cpu scheduling in os

Computer Science

CPU Scheduling Algorithms in OS (Operating System)


Gurneet Kaur

Data Science Consultant at almaBetter

people11 mins


Published on29 Aug, 2023

In the intricate symphony of computers, the CPU plays the role of the conductor, orchestrating tasks for optimal performance. CPU scheduling in Operating System is the art of juggling these tasks, ensuring the show runs smoothly. It's like managing a busy restaurant—seating guests, taking orders, and delivering dishes in a way that maximizes efficiency.

Think of CPU scheduling algorithms in OS as the maestros of this operation, deciding who gets attention and when. Various strategies include First-Come-First-Serve (FCFS), Round Robin, and Priority Scheduling. Each brings a unique flavor, ensuring no task goes unserved.

However, not all tasks are created equal. Some require a swift response, while others can wait their turn. This is where criteria like turnaround time and waiting time come into play, helping us balance fairness and efficiency.

Just as a symphony comprises different sections, the OS uses techniques like Segmentation to manage memory, keeping data harmony intact. And remember, even in the world of technology, there's a chance of deadlock—like a musical standoff where no musician can move forward.

So, as we delve into the intricacies of CPU scheduling, remember that it's the invisible hand behind your computer's rhythm. It ensures that tasks blend seamlessly, keeping your system humming like a beautifully conducted melody.

What is CPU Scheduling in OS?

CPU Scheduling in OS

CPU Scheduling in OS

What is CPU Scheduling in OS? So let’s go ahead and define CPU Scheduling in OS. At the heart of your computer's performance lies a crucial operation known as CPU scheduling. Think of it as a traffic cop directing vehicles on a busy road. In the operating system realm, CPU scheduling in OS  is the traffic cop, managing various tasks and processes that are vying for attention from the central processing unit (CPU).

Imagine you're running multiple applications simultaneously—editing a document, playing music, and browsing the web. Each of these tasks requires CPU time to execute. CPU Scheduling in Operating System allocates time slices to these tasks in a way that seems seamless to you, the user. It ensures that your music doesn't stutter while you're typing and that your web pages load without a hitch.

To make this magic happen, various algorithms come into play. These algorithms, like the choreography of a dance, decide the order in which tasks get their turn on the CPU stage. Some algorithms prioritize fairness, giving each task an equal time, while others prioritize urgent tasks, ensuring your online video call remains smooth.

As with any performance, there are criteria for success. In CPU scheduling, factors like turnaround time and waiting time measure the effectiveness of these algorithms. The goal is to keep these numbers low, indicating that tasks are executed swiftly without delay.

Ultimately, CPU scheduling in OS is like the conductor of a grand orchestra. It ensures that the multitude of tasks your computer handles are orchestrated harmoniously, creating a smooth and efficient user experience. Just as an orchestra can't perform without a conductor, your computer's processes can't work in harmony without the guidance of CPU scheduling.

CPU Scheduling Algorithms in OS: Explained with Examples

CPU Scheduling Algorithms

CPU Scheduling Algorithms

CPU scheduling algorithms in Operating System play a vital role in the complex world of operating systems. These algorithms are like ballet choreographers, determining the sequence in which tasks are performed on the CPU. Think of it as a chef preparing a multi-course meal—the order in which dishes are served can affect the overall dining experience.

There are various CPU scheduling algorithms in OS with examples, each with its unique style. Let's take a look at a couple of them.

1. First-Come-First-Serve (FCFS): This algorithm operates as the name suggests. Imagine a queue at an ice cream parlor—the first person in line gets served first. Similarly, in FCFS, the task that arrives gets CPU time. It's simple and fair but can lead to longer waiting times for later-arriving tasks.

2. Round Robin: This algorithm adds a bit of variety to the mix. Imagine a round-robin-style game where players take turns. In round-robin scheduling, tasks are given equal time slices, ensuring no task hogs the CPU too long. It's like giving each player a fair share of the playground.

These examples showcase how different algorithms can impact task execution. Just as a choreographer chooses dance steps to fit the music, an OS chooses scheduling algorithms to suit its purpose. The choice of algorithm can affect the speed of execution, the fairness of resource distribution, and more.

By delving into these algorithms, we uncover the intricacies of CPU scheduling—how it can balance tasks efficiently, prevent bottlenecks, and keep your system running smoothly. Like a well-coordinated ballet, where each dancer's performance contributes to the overall beauty, CPU scheduling algorithms in OS contribute to the harmony of your computer's operation.

Types of CPU Scheduling in OS: Finding the Right Fit

Once you’re clear with the question about what is CPU Scheduling in Operating System, we’ll dive into The types of CPU Scheduling in OS. Like a chef selects ingredients to craft the perfect dish, an operating system carefully selects CPU scheduling in Operating System strategies to ensure efficient task execution. These strategies are akin to different recipes, each catering to specific scenarios and priorities.

1. First-Come-First-Serve (FCFS): Imagine a line forming at a food truck. The first person in line gets their order fulfilled first. FCFS works similarly. The first process to arrive gets the CPU's attention before others in the bar.

2. Shortest Job Next (SJN): Consider it a buffet where you choose the shortest queue to get your food faster. SJN prioritizes the task with the shortest execution time, leading to quicker completion.

3. Priority Scheduling: Just as VIPs get special treatment, priority scheduling assigns priority levels to tasks. Higher-priority tasks get the CPU's attention first. It's like accommodating urgent guests at a busy restaurant.

4. Round Robin: Picture a carousel where each rider gets a turn before moving to the next. Round Robin scheduling allots a fixed time slice to each task, ensuring fairness among all functions.

5. Multilevel Queue Scheduling: Imagine a multi tiered cake stand, with each tier representing a different type of task. Tasks are divided into queues based on their characteristics, and each queue has its scheduling algorithm.

6. Multilevel Feedback Queue Scheduling: Consider this a marathon or sprint. Tasks start in one queue and move to other queues with varying priorities based on their behavior and execution time.

By exploring these strategies, we gain insight into the OS's decision-making process—how it chooses which task to serve next and how it balances the needs of different processes. Just as a chef's expertise lies in selecting the proper methods for each dish, an operating system's efficiency lies in choosing the right scheduling strategy for each situation.

CPU Scheduling Criteria in OS: Balancing Act for Smooth Execution

CPU Scheduling Criteria

CPU Scheduling Criteria

In the bustling realm of operating systems, CPU scheduling criteria in OS stands as the performance judges. Picture a talent show where acts are judged by their individual performance and the harmony they create together. Similarly, CPU scheduling in OS criteria evaluates tasks individually and how they come together to create a seamless user experience.

1. Turnaround Time: Imagine a relay race. Turnaround time is when the baton is passed to when the runner finishes the race. Similarly, in CPU scheduling, it's the time taken from the submission of a task to its completion. Lower turnaround time means faster execution.

2. Waiting Time: Consider it time spent in a queue. When a task waits for its turn to execute, it accumulates waiting time. Lower waiting time translates to jobs getting served more promptly.

3. Response Time: Imagine a conversation—quick responses keep the dialogue flowing. In computing, response time is the delay between requesting and receiving a response. Low response time ensures fast application performance.

4. Throughput: Picture a factory churning out products. Throughput refers to the number of tasks finished within a given timeframe. High throughput indicates efficient resource utilization.

These criteria act as the referees, ensuring tasks are served reasonably and efficiently. Just as a well-balanced orchestra creates a harmonious melody, a well-balanced CPU scheduling algorithm in OS ensures that your computer's tasks come together seamlessly, delivering a performance of optimal efficiency.

Segmentation in OS: Enhancing Memory Utilization

Segmentation in OS

Segmentation in OS

Imagine a library organizing books by categories, making it easier to find the right one. Segmentation in OS follows a similar principle, enhancing memory utilization by breaking down tasks into manageable chunks.

Segmentation Defined: Just as a book can be divided into chapters, a program can be divided into segments. Each segment corresponds to a different program part, like code, data, or stack. This technique allows for more efficient memory allocation.

Example: Think of a cooking recipe. Each step requires different ingredients and utensils. Similarly, a program's code segment might need read-only access, while the data segment needs read-and-write access. Segmentation grants each segment the appropriate permissions, boosting security.

Memory Utilization: Imagine a puzzle. Segmentation pieces fit together like a jigsaw, making the most of available space. By allocating memory based on the actual size of each segment, this technique minimizes wastage and fragmentation.

Segmentation plays a vital role in memory management, ensuring that programs run smoothly without stepping on each other's toes. It's like hosting a dinner party—having separate tables for appetizers, main courses, and desserts keeps everything organized and efficient. As segmentation optimizes memory, our dinner party segmentation optimizes guest comfort and enjoyment.

Deadlock in OS: Preventing Standstill Scenarios

Deadlock in OS

Deadlock in OS

Imagine a traffic intersection where cars from different directions are stuck, and no one can move forward. Deadlock in OS is a similar scenario, where processes are entangled in a situation where none can proceed.

Defining Deadlock: Just as cars block each other at an intersection, processes can deadlock when they're each waiting for resources that the others possess. It's like a Mexican standoff—each process remains for another to release a resource.

Real-World Example: Think of a printer shared by two departments. If one department locks the printer and waits for additional resources, the other department can't use it, leading to a deadlock. The system's stuck until one of them gives up the printer.

Addressing Deadlock: Just as a traffic cop intervenes to untangle traffic, the OS employs strategies to break deadlocks. One method is resource preemption—taking away resources from one process to allocate to another. However, this can lead to inefficiency or conflicts.

Deadlock prevention and avoidance strategies are like anticipating traffic congestion and rerouting vehicles. These strategies ensure that processes don't reach deadlock scenarios in the first place, maintaining a smooth flow of tasks.

Deadlock is a puzzle the OS must solve to ensure systems run without getting caught in a stalemate. It's like managing a busy train schedule—ensuring trains move seamlessly without getting stuck on the tracks. Similarly, the OS keeps processes moving, preventing standstill scenarios for optimal performance.

ROM and Its Role in CPU Scheduling

ROM is a non-volatile memory that stores essential data even when the computer is turned off. Its influence in CPU scheduling in OS is akin to a conductor's sheet music, guiding the orchestration of tasks.

Defining ROM: Much like a reference book, ROM is a memory chip that stores fixed data. This data includes essential instructions and algorithms crucial for various system functions.

Role in CPU Scheduling: In CPU scheduling, ROM serves as a repository of scheduling algorithms, rules, and criteria. When the scheduler decides which task should run next, it consults this stored knowledge in ROM.

Example: Think of ROM as a rulebook in a game. Just as players follow the rules to keep the game fair, CPU scheduling algorithms in OS  adhere to the guidelines stored in ROM to ensure balanced task execution.

ROM ensures consistency in CPU scheduling, providing a standardized approach to task management. It's like a navigator for the operating system, guiding it through the complex terrain of task prioritization. While it might not be directly visible, ROM's influence is woven into a smooth and efficient system performance fabric.


In the dynamic universe of an operating system, CPU scheduling in Operating System reigns as the conductor of a finely tuned symphony. This symphony orchestrates a seamless performance through informed CPU scheduling algorithms in OS that carefully coordinate tasks' execution. The intertwining of processes with varying needs and priorities mirrors a harmonious musical composition guided by the intricate algorithms at play.

CPU scheduling in OS acts as a balancing act, ensuring that tasks receive their due attention while maintaining fairness. Just as a conductor directs different sections of an orchestra, CPU scheduling algorithms in OS assign CPU time to processes, optimizing resource utilization.

Coordinated management is paramount in CPU scheduling. An OS efficiently navigates between the diverse requirements of processes, mirroring how an orchestra harmonizes the sounds of individual instruments. The spotlight is shared, enhancing the overall performance.

Refinement is the hallmark of effective CPU scheduling in Operating System criteria. Like a stage production's quality control, metrics like turnaround and waiting times shape the performance. The system's efficiency is maximized through these metrics, echoing the precision of a well-executed show.

The role of Read-Only Memory (ROM) is underlying the brilliance of CPU scheduling. ROM's presence in CPU scheduling algorithms in OS often goes unnoticed, yet it holds the crucial guidelines that drive scheduling decisions.

As users interact with their devices, the rhythm of CPU scheduling in OS hums in the background, maintaining seamless multitasking and preventing bottlenecks. The OS achieves sophisticated choreography through techniques like segmentation and deadlock management.

In essence, CPU scheduling in Operating System defines the fluidity of task execution in an operating system, much like a conductor shaping the mood of a musical piece. It embodies the essence of efficient multitasking, making the digital symphony of your computer's operations possible.

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