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Recent questions tagged page-replacement

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61

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 26 (Page No. 256)
A student in a compiler design course proposes to the professor a project of writing a compiler that will produce a list of page references that can be used to implement the optimal page replacement algorithm. Is this possible? Why or why not? Is there anything that could be done to improve paging efficiency at run time?

admin asked in Operating System Oct 26, 2019

by admin

304 views

1 vote

4 answers

62

UGC NET CSE | June 2019 | Part 2 | Question: 43
Consider that a process has been allocated $3$ frames and has a sequence of page referencing as $1, 2, 1, 3, 7, 4, 5, 6, 3, 1$. What shall be the difference in page faults for the above string using the algorithms of LRU and optimal page replacement for referencing the string? $2$ $0$ $1$ $3$

Arjun asked in Operating System Jul 2, 2019

by Arjun

4.2k views

2 votes

0 answers

63

Vani Question Bank:Operating System

Hirak asked in Operating System May 9, 2019

by Hirak

262 views

0 votes

0 answers

64

Self doubt
Can anyone explain me the working of NRU & SECOND CHANCE REPLACEMENT ALGORITHM.

Jyoti Kumari97 asked in Operating System Jan 15, 2019

by Jyoti Kumari97

166 views

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0 answers

65

MadeEasy Workbook: Operating System - Page Replacement
Assume there are 5 frames and consider the following reference string find the number of page faults using NRU page replacement algorithm. 3,2,3, 0,8,4,2,5,0,9,8,3,2

Jyoti Kumari97 asked in Operating System Jan 15, 2019

by Jyoti Kumari97

523 views

0 votes

1 answer

66

UGC NET CSE | December 2018 | Part 2 | Question: 72
Suppose for a process $P$, reference to pages in order are $1, 2, 4, 5, 2, 1, 2, 4$. Assume that main memory can accomodate $3$ pages and the main memory has already $1$ and $2$ in the order $1$ ... Replacement Algorithm is used then the number of page faults that occur to complete the execution of process $P$ is $4$ $3$ $5$ $6$

Arjun asked in Operating System Jan 2, 2019

by Arjun

2.2k views

0 votes

1 answer

67

What is the reason for Belady's Anamoly
What is the reason for Belady’s Anomaly,I am aware that it is not a stack based algorithm and for a certain set of pages it shows this anomaly where the increase in page frame increases the page fault rate.

sripo asked in Operating System Dec 28, 2018

by sripo

900 views

0 votes

0 answers

68

Page replacement implementation
Do we need to cover page replacement implementations for gate? Please suggest

Mayankprakash asked in Operating System Dec 24, 2018

by Mayankprakash

371 views

1 vote

2 answers

69

OS Optimal Page replacement
How the value is 36? im getting 39.

muthu kumar asked in Operating System Dec 15, 2018

481 views

0 votes

1 answer

70

Galvin #page fault service time #memory management #disk access

gourav94240 asked in Operating System Oct 19, 2018

1.5k views

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0 answers

71

#OS doubt
State True/False:- A Page replacement algorithm suffers from Belody's anomoly when it is not a stack algorithm. how to identify a stack algorithm? Is LRU stack algorithm? Is FIFO stack algorithm?

Naveen Kumar 3 asked in Operating System Oct 1, 2018

by Naveen Kumar 3

406 views

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0 answers

72

Self doubt
"FIFO sometimes can support stack property" And sometimes not and so,it will fall in bealady's anomaly Why is it so ?

Prince Sindhiya asked in Operating System Sep 30, 2018

by Prince Sindhiya

153 views

1 vote

1 answer

73

Os doubt
A demand paging system requires Sending trap to OS, bring the new page from LAS to PAS,updating page tables,then signaling CPU to restart the instruction time 125 time units if page is not dirty and 400 times units of page fault service time if it is a dirty page. ... m. It is observed that average access time is 50 time units. Then, the value of m is ______? [upto four decimal places]

Shivani gaikawad asked in Operating System Sep 29, 2018

by Shivani gaikawad

582 views

0 votes

0 answers

74

Page replacement
Do we have to study page replacement algorithm implementation...Is it important for gate? Please suggest

Mayankprakash asked in Operating System Sep 22, 2018

by Mayankprakash

144 views

2 votes

1 answer

75

MadeEasy Test Series: Operating System - Page Replacement
Consider a demand paged memory system, page table is held in registers. It takes 800 nsec to service a page fault if empty page is available or replaced page is not modified and 950 nsec if the replaced page is modified, ... modified 85% of time and page faultrate is 20% then average memory access time is ________. (Upto 1 decimal place)

jhaanuj2108 asked in Operating System Aug 14, 2018

2.4k views

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0 answers

76

Virtual Memory
An operating system supports a paged virtual memory, using a central processor with a cycle time of 1 microsecond. It costs an additional 1 microsecond to access a page other than the current one. Pages have 1000 words, and the paging device is a ... anybody explain.. Also, I am getting highly frustrated over such questions. Please tell me how to solve these questions correctly?

Harsh Kumar asked in Operating System Aug 13, 2018

444 views

0 votes

1 answer

77

Belady's Anomaly
Well, I am not sure that wether the Second chance algorithm suffers from Beladys anomaly. But after giving a thought i think that it may suffer from beladys anomaly because it can also sometimes work as FIFO exactly if reference bit becomes Zero for some set of Pages ?? Please Clarify :)

Na462 asked in Operating System Jul 9, 2018

by Na462

2.0k views

3 votes

3 answers

78

ISRO2018-20
Determine the number of page faults when references to pages occur in the order $1,2,4,5,2,1,2,4.$ Assume that the main memory can accommodate $3$ pages and the main memory already has the pages $1$ and $2,$ with page $1$ brought earlier than page $2.$ (assume LRU i.e., Least-Recently-Used algorithm is applied) $3$ $4$ $5$ None of the above

srestha asked in Operating System Apr 22, 2018

2.8k views

1 vote

1 answer

79

page replacemment policy
A system uses optimal policy for a page replacement. It has 4 page frames with no pages loaded to begin with. Consider the following scenario Case-1: System first accesses 200 distinct pages in sequential order and then access same 200 distinct ... access same 200 distinct page in reverse order. The difference in the number of faults occurred in both case are _________.

_anu asked in Operating System Jan 24, 2018

by _anu

379 views

1 vote

1 answer

80

MadeEasy Test Series 2018: Operating System - Page Replacement
Consider a computer system having 20 physical page frames numbered from 1 to 20 which are initially empty. Now, a program accesses the pages numbered 1, 2 ..........100 twice. The number of page fault generated by optimal page replacement policy is __________.

Ajay Jadhav asked in Operating System Jan 23, 2018

1.2k views

3 votes

1 answer

81

LRU page replacement policy
Self doubt: What is the rule or keyb point we should keep in mind while solving problems on LRU page replacement algorithm? Please explain with examples.

Sona Barman asked in Operating System Jan 18, 2018

466 views

1 vote

1 answer

82

Page Replacement
Could anyone give an example.

dragonball asked in Operating System Jan 12, 2018

371 views

1 vote

1 answer

83

Page Replacement
Consider a simple system running a single process. The size of physical frames and logical pages is 16B. The RAM can hold 3 physical frames. The virtual addresses of the process are 6 bit in size. The program generates the following 20 virtual address ... frames in RAM is initially empty and donot map to any logical page. Calculate the number of page fault ib LRU replacement policy

srestha asked in Operating System Jan 10, 2018

557 views

0 votes

0 answers

84

Beladys anamoly
"if an algorithm has stack property then it never falls into Beladys Anomaly" Is their any simple proof to this? Also I wanna know if it's one way or two way implication. Thanks.

Mahendra Singh Kanya asked in Operating System Dec 15, 2017

by Mahendra Singh Kanya

1.0k views

0 votes

1 answer

85

Page Replacement
Consider a page reference string for a process with m frames. The length of the page reference string is p with n distinct page numbers occurring in it. For any page replacement algorithms, What is lower and upper bound on the number of page faults? (A) m, n (B) p, m (C) n, p

ankitgupta.1729 asked in Operating System Dec 15, 2017

by ankitgupta.1729

767 views

6 votes

0 answers

86

OS Galvin - Doubt
Strangely, if we let $S^R$ be the reverse of a reference string S, then the page-fault rate for the OPT algorithm on S is the same as the page-fault rate for the OPT algorithm on $S^R$ . Similarly, the page-fault rate for the LRU algorithm on S is the same as ... time, rather than forward." So, shouldn't it be: page-fault-rate(OPT($S$)) = page-fault-rate(LRU($S^R$)) ???

Rishabh Gupta 2 asked in Operating System Nov 26, 2017

by Rishabh Gupta 2

890 views

2 votes

1 answer

87

nikkey123 asked in Operating System Nov 19, 2017

380 views

2 votes

2 answers

88

FIFO PAGEFAULTS
Given the following stream of page references by an application, calculate the number of page faults the application would incur with the FIFO page replacement algorithms. Assume that all pages are initially free. 3 physical pages available. Reference Stream: A B C D A B E A B C D E B A B

Parshu gate asked in Operating System Nov 11, 2017

1.3k views

5 votes

2 answers

89

#Page Faults
The address sequence generated by tracing a particular program executing in a pure demand paging system with 200 records per page with 1 free main memory frame is recorded as follows: 0100, 0139, 0209, 0430, 0237, 0578, 0500, 0730, 0799, 0600 The number of page faults are ________.

Tuhin Dutta asked in Operating System Oct 9, 2017

1.1k views

1 vote

1 answer

90

Basic Optimal page replacement policy doubt.
Consider page references, 1,2,3,5,2,3,4 and number of frames = 3. In the end will the frame contain 4,2,3 or 5,4,3 ?

Xylene asked in Operating System Aug 11, 2017

by Xylene

1.0k views

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