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.

1. FCFS
FIRST-COME-FIRST-SERVE

2. About FCFS
 Definition. It is the simplest CPU scheduling algorithm.
 With this algorithm, processes are assigned the CPU in
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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