process	burst time	arrival time	priority
P1	9	0	5
P2	3	1	1
P3	5	6	4
P4	1	4	3
P5	4	3	2

 

1.FCFS

P1

P2

P3

P4

P5

0                    9       12          17  18    22

The waiting time is (0+9+12+17+18)/5=11.2ms

 

2. SJF

Preemptive（shortest-job-first scheduling）:

P4

P2

P5

P3

P1

0   1     4       8        13                        22

 

The waiting time is (0+1+4+8+13)/5=5.2ms

 

Preemptive（shortest-remaining-time-first scheduling）:

P1

P2

P5

P4

P3

P1

0   1     4      8   9        14                    22

 

The waiting time is [0+0+(4-3)+(8-4)+(9-6)+(14-1)]/5=4.2ms

 

3.priority scheduling

P2

P5

P4

P3

P1

0     3       7    8         13                      22

 

The waiting time is (0+3+7+8+13)/5=5.2ms

 

4.Round-Robin

 

P1

P2

P3

P4

P5

P3

P5

P1

P1

0     3      6      9   10    13   15   16     19     22

 

The waiting time is (0+3+6+9+10+13+15+16+19)/5=18.2ms