![]() ![]() When the CPU gets free, it is assigned to the process at the head or start of the queue.Ĭonsider the following set of processes/jobs which arrive at time 0, with the length of the CPU burst that is given in milliseconds: Process list Burst - Time P 1 24 P 2 3 P 3 3 As a process enters the ready queue, its Process Control Block is linked with the tail of the queue. The execution of the FCFS policy is easily managed with a FIFO queue. With this method, the process which requests the CPU first, that process gets allocated to the CPU first. Special thanks to Ami Jangid for contributing to this article on takeUforward.First-Come, First-Served Scheduling (FCFS) Algorithmīy far the easiest and simplest CPU scheduling algorithm is the first-come, first served (FCFS) scheduling technique. It provides minimum average time among all scheduling algorithms. In SRTF, processes are scheduled according to the shortest remaining time. SRTF is the preemptive version of SJF scheduling. It is impractical since it is not possible to know the burst time of every process in the ready queue in advance.May cause high waiting and response times for CPU-bound processes.The reason we schedule the processes which take less time first. The minimum average waiting time among all scheduling algorithms. ![]() *Waiting time = Turn around time – Burst time * Turn around time = Completion time – Arrival time ![]() This runs till completion followed by P2. Then P3 is scheduled whose burst time is 5. Its burst time is 2 more than the remaining time of P2 so P2 is continued to be scheduled until completion. The same comparison is done Since P1 has 3 remaining unit times which is less than P2, it is continued to be scheduled. So when the new process arrives, the remaining burst time of the running process is compared with the burst time of the newly arrived process and if the remaining time of P0 is more than P0 is preempted and P1 is scheduled. At time 1 there is one more process that arrived. It is a preemptive version of SJF(Shortest Job First) scheduling. In the shortest remaining time first scheduling, whenever the new job arrives we compare its burst time with the remaining time of the currently running job and if it is less, then we preempt the currently running job and schedule the newly arrived process. This article talks about SRTF scheduling in detail. In the shortest remaining time first scheduling, jobs are scheduled according to the shortest remaining time. ![]()
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