Relation in FCFS and Round Robin Scheduling Algorithm Last Updated : 18 Sep, 2020 Comments Improve Suggest changes Like Article Like Report In this article, we'll see how FCFS is special kind of Round Robin Algorithm and Round Robin is special kind of FCFS Algorithm. Also, we will cover the relation with each other. Let's discuss one by one. First Come First Serve (FCFS) Scheduling Algorithm : FCFS is simplest of CPU Scheduling Algorithm which executes process that comes first. It is non-preemptive algorithm. Process that comes in ready queue first gets to be executed by the CPU first, then second one, then third one, and so on. The arrival time of processes is deciding factor here. Ready queue acts like FIFO (First In First Out) queue. FCFS Scheduling Algorithm with Gantt Chart Round Robin (RR) Algorithm: The Round Robin scheduling algorithm is preemptive scheduling algorithm. It uses concept of time slice or time quantum. Process at the beginning of ready queue gets chance to be executed first but only for span of one-time quantum. As new and more processes get added to ready queue, ongoing process gets preempted and gets added to end of ready queue. Next process gets the chance, again for span of one-time quantum. This algorithm is designed for time-sharing systems. Round robin algorithm with time slice = 4 FCFS is a special kind of RR Algorithm : FCFS with large time quantum acts like an RR algorithm. Imagine an RR algorithm with time slice so large that it is equal or larger than burst time of longest process, then each process will be executed in manner they arrive into the ready queue. There will be no preemption. It will act just like FCFS Algorithm. So, we say that FCFS is special kind of RR algorithm when FCFS has large time quantum. Note - Here, we do not say that RR is not special kind of FCFS because FCFS does not support concept of time quantum. RR can be special type of FCFS but it has separate condition that is mentioned below. RR is special kind of FCFS Algorithm : In RR, when process is not completely executed within the one-time quantum, it gets preempted and is added again to ready queue with new arrival time. To the ready queue, it is new process being entered. So, RR is executing them one by one as they enter ready queue. No other type of priority is being used here. So, we say that RR is a special kind of FCFS algorithm when job is preempted and rejoins the ready queue with new arrival time. Comment More infoAdvertise with us Next Article Relation in FCFS and Round Robin Scheduling Algorithm srishtiganguly1999 Follow Improve Article Tags : Operating Systems GATE CS Operating Systems-CPU Scheduling Similar Reads Relation in FCFS and Preemptive Priority Scheduling Algorithm In this article, we will see how FCFS is a special kind of Priority Preemptive Scheduling Algorithm. Also, we will cover the relation with each other. Let us discuss one by one. 1. First Come First Serve (FCFS) Scheduling Algorithm : FCFS is the simplest of CPU Scheduling Algorithm which executes th 4 min read Relation between Preemptive Priority and Round Robin Scheduling Algorithm In this article, we'll try to establish the relation between Round Robin and Preemptive Priority Scheduling Algorithm. Let's discuss the algorithms one by one first and then establish how Round Robin is a special kind of Preemptive Priority Scheduling Algorithm. Prerequisite - CPU Scheduling | Diffe 2 min read SCAN (Elevator) Disk Scheduling Algorithms In the SCAN Disk Scheduling Algorithm, the head starts from one end of the disk and moves towards the other end, servicing requests in between one by one and reaching the other end. Then the direction of the head is reversed and the process continues as the head continuously scans back and forth to 12 min read Comparison of Different CPU Scheduling Algorithms in OS A scheduling algorithm is used to estimate the CPU time required to allocate to the processes and threads. The prime goal of any CPU scheduling algorithm is to keep the CPU as busy as possible for improving CPU utilization. Scheduling Algorithms 1. First Come First Serve(FCFS): As the name implies t 5 min read Difference between Multi Level Queue (MLQ) Scheduling and Round Robin (RR) algorithms Queue Scheduling refers to the process of managing and organizing tasks (or processes) that need to be executed by a system. In an operating system, tasks are often placed in queues waiting for CPU to execute them. Queue scheduling helps the system decide which task to run next, and in what order, e 4 min read Difference between First Come First Served (FCFS) and Round Robin (RR) Scheduling Algorithm First Come First Served Scheduling Algorithm: First Come First Served (FCFS) is the simplest and non-preemptive scheduling algorithm. In First Come First Served (FCFS), the process is allocated to the CPU in the order of their arrival. A queue data structure is used to implement the FCFS scheduling 2 min read Difference between Shortest Job First (SJF) and Round-Robin (RR) scheduling algorithms The performance of the multiprocessor system and time-sharing system rely upon CPU scheduling algorithm. Some of the well known efficient CPU scheduling algorithms are Round Robin scheduling (RR), Shortest job first(SJF), Preemptive version of SJF(SRTF), First Come First Serve (FCFS) etc. As of now, 4 min read Round Robin Scheduling in Operating System Round Robin Scheduling is a method used by operating systems to manage the execution time of multiple processes that are competing for CPU attention. It is called "round robin" because the system rotates through all the processes, allocating each of them a fixed time slice or "quantum", regardless o 5 min read Longest Job First (LJF) CPU Scheduling Algorithm Longest Job First (LJF) is a non-preemptive scheduling algorithm. This algorithm is based on the burst time of the processes. The processes are put into the ready queue based on their burst times i.e., in descending order of the burst times. As the name suggests this algorithm is based on the fact t 5 min read LOOK Disk Scheduling Algorithm The LOOK Disk Scheduling Algorithm is the advanced version of the SCAN (elevator) disk scheduling algorithm which gives slightly better seek time than any other algorithm in the hierarchy (FCFS->SRTF->SCAN->C-SCAN->LOOK). It is used to reduce the amount of time it takes to access data on 13 min read Like