Question

You are given the independent jobs A(5), B(7), C(10), D(12), E(6), F(4), G(3).

(a) Using the alphabetical order priority list above, if the jobs are scheduled on 3 processors, what is the completion time?

(b) If the decreasing time algorithm is used to schedule the jobs on 3 processors, what is the completion time?

(c) If the decreasing time algorithm is used to schedule the jobs on 3 processors, which is the second job scheduled on processor 1?

A

b

c

d

e

f

g

Answer 1

First we will sort the processes according to the alphabetical order and then in the decreasing time order.

Alphabetical order

Process	Time
A	5
B	7
C	10
D	12
E	6
F	4
G	3

Decreasing time

Process	Time
G	3
F	4
A	5
E	6
B	7
C	10
D	12

a) Therefore by the alphabetical queuing, the queues in the three processors would be

Process 1:A,D

Process 2:B,E

Process 3:C,F,G

Now the completion time of each of these queues is respectively (5+12)=17, (7+6)=13, (10+4+3) = 17. Hence the completion time would be the maximum time in these queues, which is 17.

b and c) Similarly for decresing time process:

Process 1:G,E,D

Process 2:F,B

Process 3:A,C

Now the completion time of each of these queues is respectively (3+6+12)=21, (7+4)=11, (5+10) = 15. Hence the completion time would be the maximum time in these queues, which is 21.

Also the second job scheduled on processor 1 is E.