Preemptive scheduling – Gate 2025 – TOC previous year solved question Paper.

Lui Kreyszig

2 weeks ago

https://www.gyanodhan.com/video/7B7.%20GATE%20CSEIT/Operating%20System/401.%20Preemptive%20scheduling%20-%20Gate%202009%20-%20TOC%20previous%20year%20solved%20question%20Paper.mp4

Contents

0.1 Preemptive Scheduling – GATE 2025 | TOC Previous Year Solved Question

1 क्या होता है Preemptive Scheduling?
- 1.1 Key Features:
2 Common Preemptive Algorithms:
3 GATE Previous Year Solved Question (Example)
4 Concept Check:
5 Summary:
- 5.1 Want a PDF version with solved examples + practice questions?

Preemptive Scheduling – GATE 2025 | TOC Previous Year Solved Question

Topic: Operating System (OS) – Preemptive CPU Scheduling
Exam Focus: GATE CSE / IT 2025
Category: Theory of Computation (TOC often refers to OS in GATE context when dealing with scheduling topics)

क्या होता है Preemptive Scheduling?

Preemptive Scheduling एक CPU scheduling तकनीक है जिसमें running process को बीच में रोककर किसी दूसरे higher priority या ready process को CPU दिया जाता है।

Key Features:

Feature	Description
Preemption	हाँ (Yes) – Process को बीच में interrupt किया जा सकता है
Control	OS के पास होता है
Response Time	बेहतर
Context Switching	ज़्यादा होता है (CPU overhead बढ़ता है)

Common Preemptive Algorithms:

Round Robin (RR)
Shortest Remaining Time First (SRTF)
Preemptive Priority Scheduling

GATE Previous Year Solved Question (Example)

GATE CSE Question (Simplified):

GATE Year: 2017
Question Type: Numerical
Topic: Preemptive Scheduling – SRTF

Q:

Consider the following set of processes with arrival time and burst time:

Process	Arrival Time	Burst Time
P1	0 ms	7 ms
P2	2 ms	4 ms
P3	4 ms	1 ms
P4	5 ms	4 ms

Use Shortest Remaining Time First (Preemptive) scheduling.
What is the average waiting time?

Solution Step-by-Step:

Step 1: Gantt Chart

Time	Running Process
0-2	P1 (7→5)
2-4	P2 (4→2)
4-5	P3 (1)
5-6	P2 (2→1)
6-7	P2 (1→0)
7-11	P4 (4)
11-13	P1 (5→3)
13-15	P1 (3→1)
15-17	P1 (1→0)

Completion Time (CT)

Process	CT	TAT (CT – AT)	WT (TAT – BT)
P1	17	17 – 0 = 17	17 – 7 = 10
P2	7	7 – 2 = 5	5 – 4 = 1
P3	5	5 – 4 = 1	1 – 1 = 0
P4	11	11 – 5 = 6	6 – 4 = 2

Average Waiting Time:

= (10 + 1 + 0 + 2) / 4
= 13 / 4 = 3.25 ms

Concept Check:

Preemptive = Process को interrupt किया जा सकता है
Waiting Time = Turnaround Time – Burst Time
SRTF always selects the process with minimum remaining time

Summary:

GATE Relevance: Highly important topic
Common Question Format: Gantt chart-based, waiting time, turnaround time
Pro Tip: Practice SRTF with multiple process arrivals

Want a PDF version with solved examples + practice questions?

Just ask, and I’ll generate a downloadable file or quiz for practice.

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f4d8.png" alt="📘" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Preemptive Scheduling – GATE 2025 | TOC Previous Year Solved Question

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/2699.png" alt="⚙" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> क्या होता है Preemptive Scheduling?

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f511.png" alt="🔑" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Key Features:

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f4cc.png" alt="📌" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Common Preemptive Algorithms:

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f4dd.png" alt="📝" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> GATE Previous Year Solved Question (Example)

GATE CSE Question (Simplified):

Q:

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/2705.png" alt="✅" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Solution Step-by-Step:

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f4ca.png" alt="📊" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Step 1: Gantt Chart

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/23f1.png" alt="⏱" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Completion Time (CT)

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f9ee.png" alt="🧮" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Average Waiting Time:

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f393.png" alt="🎓" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Concept Check:

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f4e6.png" alt="📦" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Summary:

<img src="https://s.w.org/images/core/emoji/13.0.1/72x72/1f4e5.png" alt="📥" class="wp-smiley amp-wp-843f19c" width="72" height="72" data-amp-original-style="height: 1em; max-height: 1em;"> Want a PDF version with solved examples + practice questions?