Recent questions tagged page-replacement

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31

UGC NET CSE | October 2020 | Part 2 | Question: 15
Consider a hypothetical machine with $3$ pages of physical memory, $5$ pages of virtual memory, and $<A, B, C, D, A, B, E, A, B, C, D, E, B, A, B>$ as the stream of page reference by an application. If $P$ and $Q$ are the number of ... $(P,Q)=$ _______(Assuming enough space for storing $3$ page frames) $(11,10)$ $(12,11)$ $(10,11)$ $(11,12)$

Consider a hypothetical machine with $3$ pages of physical memory, $5$ pages of virtual memory, and $<A, B, C, D, A, B, E, A, B, C, D, E, B, A, B>$ as the stream of page ...

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go_editor asked Nov 20, 2020

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2 answers

32

NIELIT 2017 DEC Scientific Assistant A - Section B: 17
Non-contiguous memory allocation splits program into blocks of memory called ________ that can be loaded in non-adjacent holes in main memory. Pages Frames Partition Segments

Non-contiguous memory allocation splits program into blocks of memory called ________ that can be loaded in non-adjacent holes in main memory.PagesFramesPartitionSegments...

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admin asked Mar 31, 2020

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2 answers

33

NIELIT 2016 MAR Scientist B - Section C: 38
Determine the number of page faults when references to pages occur in the following 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 $1$ having been brought earlier than page $2$.(LRU algorithm is used). $3$ $5$ $4$ None of these.

Determine the number of page faults when references to pages occur in the following order: $1,2,4,5,2,1,2,4$. Assume that the main memory can accommodate $3$ pages and th...

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admin asked Mar 31, 2020

0 votes

1 answer

34

NIELIT 2016 MAR Scientist B - Section C: 39
Working set$(t,k)$ at an instant of time, $t$,is The set of $k$ future references that the operating system will make The set of future references that the operating system will make in the next $'k'$ time units The set of $k$ references with high frequency The set of pages that have been referenced in the last $k$ time units

Working set$(t,k)$ at an instant of time, $t$,isThe set of $k$ future references that the operating system will makeThe set of future references that the operating system...

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admin asked Mar 31, 2020

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1 answer

35

NIELIT 2016 DEC Scientist B (CS) - Section B: 48
In which one of the following pages replacement policies, Belady's anomaly may occur? FIFO LRU Optimal MRU

In which one of the following pages replacement policies, Belady's anomaly may occur?FIFOLRUOptimalMRU

672 views

admin asked Mar 31, 2020

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2 answers

36

NIELIT 2017 DEC Scientist B - Section B: 51
The total number of page faults for the reference string $1,2,3,4,5,6,7,8,9,10$ using FIFO page replacement policy for a process, if $3$ frames are allocated to it are $9$ $10$ $8$ $11$

The total number of page faults for the reference string $1,2,3,4,5,6,7,8,9,10$ using FIFO page replacement policy for a process, if $3$ frames are allocated to it are$9$...

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admin asked Mar 30, 2020

6 votes

4 answers

37

ISRO2020-30
Consider the following page reference string. $1\ 2\ 3\ 4\ 2\ 1\ 5\ 6\ 2\ 1\ 2\ 3\ 7\ 6\ 3\ 2\ 1\ 2\ 3\ 6\ $ What are the minimum number of frames required to get a single page fault for the above sequence assuming LRU replacement strategy? $7$ $4$ $6$ $5$

Consider the following page reference string.$1\ 2\ 3\ 4\ 2\ 1\ 5\ 6\ 2\ 1\ 2\ 3\ 7\ 6\ 3\ 2\ 1\ 2\ 3\ 6\ $What are the minimum number of frames required to get a single ...

5.6k views

Satbir asked Jan 13, 2020

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38

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 54 (Page No. 261)
Write a program that will demonstrate the difference between using a local page replacement policy and a global one for the simple case of two processes. You will need a routine that can generate a page reference string ... a local one. Also, contrast the per-process page fault rate with that of the local policy approach.

Write a program that will demonstrate the difference between using a local page replacement policy and a global one for the simple case of two processes. You will need a ...

301 views

admin asked Oct 26, 2019

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39

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 40 (Page No. 259)
One of the first timesharing machines, the $DEC\: PDP-1,$ had a (core) memory of $4K\: 18-bit$ words. It held one process at a time in its memory. When the scheduler decided to run another process, the process in ... start writing (or reading) at any word, rather than only at word $0.$ Why do you suppose this drum was chosen?

One of the first timesharing machines, the $DEC\: PDP-1,$ had a (core) memory of $4K\: 18-bit$ words. It held one process at a time in its memory. When the scheduler deci...

187 views

admin asked Oct 26, 2019

2 votes

1 answer

40

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 38 (Page No. 258)
Consider the following two-dimensional array: int X[64][64]; Suppose that a system has four page frames and each frame is $128$ words (an integer occupies one word). Programs that manipulate the $X$ array fit into exactly one page and always occupy page $0.$ ... ; i < 64; i++) for (int j = 0; j < 64; j++) X[i][j] = 0;

Consider the following two-dimensional array:int X[64][64];Suppose that a system has four page frames and each frame is $128$ words (an integer occupies one word). Progra...

1.6k views

admin asked Oct 26, 2019

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41

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 37 (Page No. 258)
Suppose that two processes $A$ and $B$ share a page that is not in memory. If process $A$ faults on the shared page, the page table entry for process $A$ must be updated once the page is read into ... page fault will bring the shared page into memory? Explain. What is the potential cost of delaying the page table update?

Suppose that two processes $A$ and $B$ share a page that is not in memory. If process $A$ faults on the shared page, the page table entry for process $A$ must be updated ...

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admin asked Oct 26, 2019

2 votes

1 answer

42

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 36 (Page No. 258)
A computer has four page frames. The time of loading, time of last access, and the $R$ and $M$ bits for each page are as shown below (the times are in clock ticks): Which page will NRU replace? Which page will FIFO replace? Which page will LRU replace? Which page will second chance replace?

A computer has four page frames. The time of loading, time of last access, and the $R$ and $M$ bits for each page are as shown below (the times are in clock ticks):Which ...

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admin asked Oct 26, 2019

1 votes

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43

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 35 (Page No. 258)
How long does it take to load a $64-KB$ program from a disk whose average seek time is $5\: msec,$ whose rotation time is $5 msec,$ and whose tracks hold $1\: MB$ for a $2-KB$ page size? for a ... around the disk and the number of cylinders is so large that the chance of two pages being on the same cylinder is negligible.

How long does it take to load a $64-KB$ program from a disk whose average seek time is $5\: msec,$ whose rotation time is $5 msec,$ and whose tracks hold $1\: MB$for a $2...

375 views

admin asked Oct 26, 2019

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0 answers

44

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 34 (Page No. 257)
A student has claimed that in the abstract, the basic page replacement algorithms (FIFO, LRU, optimal) are identical except for the attribute used for selecting the page to be replaced.'' What is ... for the FIFO algorithm? LRU algorithm? Optimal algorithm? Give the generic algorithm for these page replacement algorithms.

A student has claimed that ‘‘in the abstract, the basic page replacement algorithms (FIFO, LRU, optimal) are identical except for the attribute used for selecting the...

471 views

admin asked Oct 26, 2019

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0 answers

45

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 33 (Page No. 257)
Suppose that the $\text{WSClock}$ page replacement algorithm uses a $\tau$ of two ticks, and the system state is the following: where the three flag bits $V, R,$ and $M$ stand for Valid, Referenced, and Modified, ... to page $4.$ Show the contents of the new table entries. Explain. (You can omit entries that are unchanged.)

Suppose that the $\text{WSClock}$ page replacement algorithm uses a $\tau$ of two ticks, and the system state is the following:where the three flag bits $V, R,$ and $M$ s...

896 views

admin asked Oct 26, 2019

0 votes

1 answer

46

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 32 (Page No. 257)
In the $\text{WSClock}$ algorithm of Fig. $3-20(c),$ the hand points to a page with $R = 0.$ If $\tau = 400,$ will this page be removed? What about if $\tau = 1000?$

In the $\text{WSClock}$ algorithm of Fig. $3-20(c),$ the hand points to a page with $R = 0.$ If $\tau = 400,$ will this page be removed? What about if $\tau = 1000?$

738 views

admin asked Oct 26, 2019

1 votes

0 answers

47

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 31 (Page No. 257)
Give a simple example of a page reference sequence where the first page selected for replacement will be different for the clock and $LRU$ page replacement algorithms. Assume that a process is allocated $3=\text{three}$ frames, and the reference string contains page numbers from the set $0, 1, 2, 3.$

Give a simple example of a page reference sequence where the first page selected for replacement will be different for the clock and $LRU$ page replacement algorithms. As...

350 views

admin asked Oct 26, 2019

0 votes

0 answers

48

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 30 (Page No. 257)
A small computer on a smart card has four page frames. At the first clock tick, the $R$ bits are $0111\:\: ($page $0$ is $0,$ the rest are $1).$ ... $8-bit$ counter, give the values of the four counters after the last tick.

A small computer on a smart card has four page frames. At the first clock tick, the $R$ bits are $0111\:\: ($page $0$ is $0,$ the rest are $1).$ At subsequent clock ticks...

434 views

admin asked Oct 26, 2019

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0 answers

49

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 29 (Page No. 257)
Consider the page sequence of Fig. $3-15(b)$. Suppose that the $R$ bits for the pages $B$ through $A$ are $11011011,$ respectively. Which page will second chance remove?

Consider the page sequence of Fig. $3-15(b)$. Suppose that the $R$ bits for the pages $B$ through $A$ are $11011011,$ respectively. Which page will second chance remove?

327 views

admin asked Oct 26, 2019

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50

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 28 (Page No. 257)
If $FIFO$ page replacement is used with four page frames and eight pages, how many page faults will occur with the reference string $0172327103$ if the four frames are initially empty? Now repeat this problem for$ LRU.$

If $FIFO$ page replacement is used with four page frames and eight pages, how many page faults will occur with the reference string $0172327103$ if the four frames are in...

446 views

admin asked Oct 26, 2019

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0 answers

51

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 27 (Page No. 256 - 257)
Suppose that the virtual page reference stream contains repetitions of long sequences of page references followed occasionally by a random page reference. For example, the sequence ... replacement approach that would perform much better than the $\text{LRU, FIFO, or clock} $ algorithms.

Suppose that the virtual page reference stream contains repetitions of long sequences of page references followed occasionally by a random page reference. For example, th...

332 views

admin asked Oct 26, 2019

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