CSEIT – GATE 2025 Subject – Operating System/Topic – Process Synchronization (based on Algo-3).
CSEIT – GATE 2025 Subject – Operating System/Topic – Process Synchronization (based on Algo-3).
Here is a structured and GATE-focused explanation for:
Contents
- 1 ๐ CSE/IT โ GATE 2025
- 2 ๐ Algo-3: Petersonโs Algorithm
- 2.1 โ๏ธ Shared Variables:
- 2.2 ๐จโ๐ป Code for Process Pi (i = 0 or 1):
- 2.3 โ How It Works:
- 2.4 ๐ Satisfies the 3 Conditions of Critical Section Problem:
- 2.5 ๐งช GATE-Style Example Question:
- 2.6 ๐ Summary:
- 2.7 CSEIT – GATE 2025 Subject – Operating System/Topic – Process Synchronization (based on Algo-3).
- 2.8 OPERATING SYSTEMS PROCESS SYNCHRONIZATION
- 2.9 Computer Science & Engineering Second Year
๐ CSE/IT โ GATE 2025
๐ Subject: Operating System
๐ Topic: Process Synchronization (Based on Algo-3 โ Petersonโs Algorithm)
๐ง What is Process Synchronization?
Process Synchronization is the technique used to coordinate the execution of concurrent processes that share resources. It ensures that:
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Only one process accesses the critical section (CS) at a time (Mutual Exclusion),
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The system makes progress without unnecessary delay,
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Every process eventually gets a chance (Bounded Waiting).
๐ Algo-3: Petersonโs Algorithm
๐ Used for: Synchronization between 2 processes (P0 and P1)
๐ Type: Software-based solution
๐ Key Features:
-
Guarantees mutual exclusion
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Ensures progress and bounded waiting
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No need for hardware-level atomic instructions
๐จโ๐ป Code for Process Pi (i = 0 or 1):
โ How It Works:
-
Each process sets its flag to
true
indicating its interest in entering CS. -
It gives the turn to the other process.
-
If the other process also wants to enter and itโs its turn, the current process waits.
-
This guarantees mutual exclusion.
๐ Satisfies the 3 Conditions of Critical Section Problem:
Condition | Met? | Explanation |
---|---|---|
Mutual Exclusion | โ | Only one process can enter the CS at a time. |
Progress | โ | A process not in CS doesnโt block others. |
Bounded Waiting | โ | Each process gets a turn in a finite time. |
๐งช GATE-Style Example Question:
Q: In Petersonโs algorithm for two processes P0 and P1, what ensures mutual exclusion?
A. Setting turn = 1 - i
B. The flag
array
C. The combination of flag[]
and turn
D. None of the above
โ
Correct Answer: C โ Both flag[]
and turn
are essential for mutual exclusion.
๐ Summary:
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Petersonโs Algorithm is simple but powerful.
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Itโs a frequent topic in GATE questions.
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Best understood by writing and simulating the code.
Would you like:
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A flowchart of the algorithm?
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A PDF of this explanation?
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