First-Come-First-Serve (FCFS)
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The First Come First Serve (FCFS) CPU scheduling algorithm processes jobs in the order that they arrive in the ready queue. Newly arrived processes are added to the tail of the FIFO queue. The first process in the queue is scheduled first and removed from the queue. This is the simplest scheduling algorithm to implement but can result in long average wait times for processes as later arriving processes may have to wait for all earlier processes to complete.
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First-Come-First-Serve (FCFS)
- 2. About FCFS Definition. It is the simplest CPU scheduling algorithm. With this algorithm, processes are assigned the CPU in the order they request it. Basically, there is a single queue of ready processes. Relative importance of jobs measured only by arrival time. The implementation of the FCFS policy is easily managed with a FIFO queue. When a process enters the ready queue, its PBC is linked onto the tail of the queue. The average waiting time under the FCFS policy, however, is often quite long.
- 3. Example of FCFS Example. Process AT BT WT RT TT P2 0 3 0 0 3 P4 4 2 3 3 5 P3 6 3 3 3 6 P1 2 4 1 1 5 P2 P1 P2 0 P4 P3 AWT P1 2 P4 3 4 6 7 P3 9 1.75 ART 1.75 ATT 4.75
- 4. FCFS Contributor: Ledesma, Ruth Cavite City, Philippines