Operating System Scheduling Algorithms are a core concept in computer science and form an important part of operating system theory for exams, interviews, and real-world system design. This article explains Operating System Scheduling Algorithms in simple language with clear definitions, types, and examples, making it useful as operating system scheduling algorithms notes and operating system short notes for students.
Operating System Scheduling Algorithms define the rules and methods used by the operating system to select a process from the ready queue and allocate CPU time to it. Proper scheduling helps in improving CPU utilization, reducing waiting time, and ensuring fair execution of processes. These concepts are especially important for students learning operating systems, as they frequently appear in exams, interviews, and real-time system discussions.
Operating System Scheduling Algorithms manage how the CPU allocates time among multiple processes to ensure efficient execution and system responsiveness. This guide explains core scheduling concepts, including process scheduling, preemptive and non-preemptive techniques, and popular algorithms such as FCFS, SJN, Priority, Round Robin, and Multilevel Queue scheduling, helping students and engineers understand CPU behavior in both batch and interactive operating systems.
should understand before building professional embedded applications.
A process is a program in execution. In an operating system, a process represents the active state of a program that is loaded into main memory and currently being executed by the CPU. Understanding what is a process in operating system concepts is essential before learning Operating System Scheduling Algorithms.
Each process consists of the following components:
Process scheduling in operating system refers to the method used by the OS to decide which process from the ready queue should be executed next by the CPU. The main objective of Operating System Scheduling Algorithms is to maximize CPU utilization, reduce waiting time, and improve overall system responsiveness.
The component responsible for making this decision is called the process scheduler in operating system.
CPU scheduling algorithms are strategies used by the operating system to allocate CPU time among multiple processes. These Operating System Scheduling Algorithms are broadly classified into:
In preemptive and non preemptive scheduling, a running process may or may not be interrupted depending on priority, time quantum, and system rules.
The most commonly used Operating System Scheduling Algorithms include:
These os scheduling algorithms are widely used in batch systems, time-sharing systems, and interactive operating system environments.
The fcfs scheduling algorithm, also known as first come first serve scheduling, executes processes strictly in the order of their arrival.
FCFS is one of the earliest Operating System Scheduling Algorithms used in batch operating systems.
Shortest job next scheduling, also called shortest job first scheduling, selects the process with the smallest CPU burst time for execution.
The sjn scheduling algorithm is effective mainly in batch environments.
In the priority scheduling algorithm, each process is assigned a priority value. The CPU is allocated to the process with the highest priority.
Shortest remaining time scheduling is the preemptive version of the SJN algorithm.
The srt scheduling algorithm improves response time for short processes.
The round robin scheduling algorithm is designed mainly for time-sharing systems.
Round Robin is one of the most widely used cpu scheduling algorithms in modern operating systems.
Multilevel queue scheduling divides the ready queue into multiple queues based on process type.
For example, system processes may use FCFS, while user processes use Round Robin scheduling.
The ready queue in operating system contains processes that are ready for execution but waiting for CPU allocation. All Operating System Scheduling Algorithms select processes from the ready queue.
Operating System Scheduling Algorithms are important because they:
They are methods used by the OS to decide which process runs next on the CPU.
It improves CPU utilization, system efficiency, and responsiveness.
Preemptive scheduling allows interruption of a running process, while non-preemptive does not.
There is no single best algorithm; it depends on system requirements.
Yes, these Operating System Scheduling Algorithms notes are ideal for exams, interviews, and beginners.
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This article covered Operating System Scheduling Algorithms in a structured and exam-oriented manner. By understanding cpu scheduling algorithms, process scheduling in operating system, and different scheduling techniques, students can build a strong foundation in operating system concepts.