Operating Systems · Question 15 · Hard
Operating Systems question 15
Two processes enforce mutual exclusion using only a shared variable turn (process i enters its critical section only when turn == i, and sets turn to the other process on exit). Which critical-section requirement does this strict alternation violate?
- Mutual exclusion
- Progress
- Bounded waiting
- None; it satisfies all three
Answer and explanation
Answer: B. Progress
Explanation: Strict alternation gives mutual exclusion, but a process cannot enter twice in a row even when the other process does not want the critical section. That violates progress. Peterson's solution fixes this by adding flag variables.
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