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Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?
- a)X' >= X and Y' >= Y
- b)X' >= X and Y' =< Y
- c)X' = X and Y' = YCorrect Answer
- d)X' <= X and Y' >= Y
Correct answer is option 'C'. Can you explain this answer?
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Verified Answer
Let S be the reference string and X, Y be the no. Of page fault occur ...
It is the property of Optimal and LRU page replacement that S and SR will have same number of page fault.
Also, FIFO suffer from Belady’s anomaly but LRU and Optimal do not suffer from belady’s anomaly.
Most Upvoted Answer
Let S be the reference string and X, Y be the no. Of page fault occur ...
Understanding Page Replacement Policies
Page replacement policies are crucial in managing the memory of computer systems. Two common strategies are Optimal and Least Recently Used (LRU).
Page Faults in Page Replacement Policies
- Optimal Policy (X): This policy replaces the page that will not be used for the longest period in the future. Because it has the best foresight, it typically results in fewer page faults compared to LRU.
- LRU Policy (Y): This policy replaces the page that has not been used for the longest time in the past. While effective, it can lead to more page faults compared to the optimal policy, especially in certain access patterns.
Analyzing the Reverse String
When the reference string S is reversed to form SR, the sequence of page accesses changes but the fundamental memory access patterns remain.
- Optimal Policy on SR (X): The optimal policy still operates under the same principle. Since it uses future knowledge, it can adapt to the new order of access without increasing page faults.
- LRU Policy on SR (Y): The LRU policy, however, is more constrained by past usage. While it can potentially have similar page faults in some scenarios, it may also lead to more faults if the reverse sequence results in less efficient memory usage.
Conclusion on Page Faults
- From the analysis, we conclude that the relationship holds:
- X <=>: The number of page faults under the optimal policy for S and its reverse is equal or fewer.
- Y >= Y: The number of page faults under the LRU policy for S and its reverse is equal or greater.
Thus, the correct answer is option C: X = X and Y = Y. This reflects the nature of these policies and their dependence on access patterns.
Page replacement policies are crucial in managing the memory of computer systems. Two common strategies are Optimal and Least Recently Used (LRU).
Page Faults in Page Replacement Policies
- Optimal Policy (X): This policy replaces the page that will not be used for the longest period in the future. Because it has the best foresight, it typically results in fewer page faults compared to LRU.
- LRU Policy (Y): This policy replaces the page that has not been used for the longest time in the past. While effective, it can lead to more page faults compared to the optimal policy, especially in certain access patterns.
Analyzing the Reverse String
When the reference string S is reversed to form SR, the sequence of page accesses changes but the fundamental memory access patterns remain.
- Optimal Policy on SR (X): The optimal policy still operates under the same principle. Since it uses future knowledge, it can adapt to the new order of access without increasing page faults.
- LRU Policy on SR (Y): The LRU policy, however, is more constrained by past usage. While it can potentially have similar page faults in some scenarios, it may also lead to more faults if the reverse sequence results in less efficient memory usage.
Conclusion on Page Faults
- From the analysis, we conclude that the relationship holds:
- X <=>: The number of page faults under the optimal policy for S and its reverse is equal or fewer.
- Y >= Y: The number of page faults under the LRU policy for S and its reverse is equal or greater.
Thus, the correct answer is option C: X = X and Y = Y. This reflects the nature of these policies and their dependence on access patterns.
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Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?a)X' >= X and Y' >= Yb)X' >= X and Y' =< Yc)X' = X and Y' = YCorrect Answerd)X' <= X and Y' >= YCorrect answer is option 'C'. Can you explain this answer?
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Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?a)X' >= X and Y' >= Yb)X' >= X and Y' =< Yc)X' = X and Y' = YCorrect Answerd)X' <= X and Y' >= YCorrect answer is option 'C'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?a)X' >= X and Y' >= Yb)X' >= X and Y' =< Yc)X' = X and Y' = YCorrect Answerd)X' <= X and Y' >= YCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?a)X' >= X and Y' >= Yb)X' >= X and Y' =< Yc)X' = X and Y' = YCorrect Answerd)X' <= X and Y' >= YCorrect answer is option 'C'. Can you explain this answer?.
Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?a)X' >= X and Y' >= Yb)X' >= X and Y' =< Yc)X' = X and Y' = YCorrect Answerd)X' <= X and Y' >= YCorrect answer is option 'C'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?a)X' >= X and Y' >= Yb)X' >= X and Y' =< Yc)X' = X and Y' = YCorrect Answerd)X' <= X and Y' >= YCorrect answer is option 'C'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for Let S be the reference string and X, Y be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Let SR be the reverse of S, and X' and Y' be the no. Of page fault occur using the optimal and LRU page replacement policies respectively. Which of the following is true?a)X' >= X and Y' >= Yb)X' >= X and Y' =< Yc)X' = X and Y' = YCorrect Answerd)X' <= X and Y' >= YCorrect answer is option 'C'. Can you explain this answer?.
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