Four jobs to be executed on a single processor system arrive at time 0 in the…

19962008

Four jobs to be executed on a single processor system arrive at time 0 in the order A, B, C, D. The burst CPU time requirements are 4, 1, 8, 1 time units respectively. The completion time of A under round robin scheduling with time slice of one time unit is:

  1. A.

    10

  2. B.

    4

  3. C.

    8

  4. D.

    9

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Correct answer: D

Round Robin Scheduling (Time Quantum = 1)

Processes: A, B, C, D
Arrival Time = 0 (all)
Burst Times: A=4, B=1, C=8, D=1

Execution Table

Time

Process

Remaining Burst (A,B,C,D)

0–1

A

3,1,8,1

1–2

B

3,0,8,1 (B finishes)

2–3

C

3,0,7,1

3–4

D

3,0,7,0 (D finishes)

4–5

A

2,0,7,0

5–6

C

2,0,6,0

6–7

A

1,0,6,0

7–8

C

1,0,5,0

8–9

A

0,0,5,0 (A finishes)


Gantt Chart

| A | B | C | D | A | C | A | C | A |......................................
0 1 2 3 4 5 6 7 8 9

Completion time of A = 9 time units.

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