UGC NET CSE | June 2023 | Part 2: 22

Question

 

Consider the following table of arrival time and burst time for three processes $\text{P0,P1 P2}$:

Process	arrival time	Burst time
$\text{P0}$	$0 \mathrm{~ms}$	$7$
$\text{P1}$	$1 \mathrm{~ms}$	$3$
$\text{P2}$	$2 \mathrm{~ms}$	$7$

 

The pre-emptive shortest job first scheduling algorithm is used. Scheduling is carried out only at arrival or completion of a process. What is the average waiting time for the three processes?

• A. $3 \mathrm{~ms}$
• B. $3.67 \mathrm{~ms}$
• C. $4.47 \mathrm{~ms}$
• D. $4 \mathrm{~ms}$

Answer 1

Ans : Option B -> 3.67 ms

 

P0

P1

P1

P0

P2

0    1     2                4                                10                                  17

Waiting Time : P0 --> 0 + (4-1) = 3ms, P1 --> 0, P2 --> 10-2 = 8ms

Avg Waiting time = (3 + 8 )/3 = 11/3 = 3.67ms