Cpu sheduling Algorithm

CPU scheduling is the process used by an operating system to manage the allocation of the CPU (central processing unit) to various tasks or processes. CPU scheduling algorithms determine the order in which processes are executed. Here is a brief explanation of some common CPU scheduling algorithms:

First-Come-First-Serve (FCFS): This algorithm schedules processes in the order they arrive in the ready queue. It is a non-preemptive algorithm, meaning once a process starts, it runs to completion.



Shortest Job Next (SJN): Also known as Shortest Job First (SJF), this algorithm selects the process with the shortest burst time first. It minimizes waiting time but may lead to starvation for longer processes.


Priority Scheduling: Each process is assigned a priority, and the CPU is allocated to the process with the highest priority. Priority can be determined based on factors like the process's importance or its expected execution time.


Round Robin (RR): In this algorithm, each process is assigned a fixed time slice or quantum. Processes are executed in a circular manner for one quantum, and if not completed, they are moved to the back of the queue.


Multilevel Queue Scheduling: Processes are divided into different priority levels, and each queue may use a different scheduling algorithm. For example, real-time processes might use priority scheduling, while interactive processes use round-robin.


Multilevel Feedback Queue Scheduling: Similar to multilevel queues, but processes can move between different queues based on their behavior. For example, a process that uses too much CPU time may be moved to a lower-priority queue.


Lottery Scheduling: Each process is assigned a number of lottery tickets. The scheduler randomly selects a ticket, and the process holding that ticket gets the CPU. This algorithm introduces an element of randomness.


HRRN (Highest Response Ratio Next): It selects the process with the highest response ratio, which is the ratio of waiting time to burst time. This algorithm aims to reduce response time.