Recent questions tagged memory-management - GATE Overflow

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 55 (Page No. 261 - 262)
Write a program that can be used to compare the effectiveness of adding a tag field to $TLB$ entries when control is toggled between two programs. The tag field is used to effectively label each entry with the ... for a simple (but nontrivial) input example. Plot the number of $TLB$ updates per $1000$ references.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 12 views

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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.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 5 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 53 (Page No. 261)
Write a program that demonstrates the effect of $TLB$ misses on the effective memory access time by measuring the per-access time it takes to stride through a large array. Explain the main concepts behind the ... but for an older computer with a different architecture and explain any major differences in the output.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 3 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 52 (Page No. 260 - 261)
Write a program that simulates a toy paging system that uses the $\text{WSClock}$ algorithm. The system is a toy in that we will assume there are no write references (not very realistic), and process ... references. Explain what is needed to extend the program to handle a page reference stream that also includes writes.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 23 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 51 (Page No. 260)
Write a program that simulates a paging system using the aging algorithm. The number of page frames is a parameter. The sequence of page references should be read from a file. For a given input file, plot the number of page faults per $1000$ memory references as a function of the number of page frames available.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 13 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 50 (Page No. 260)
Plot a histogram and calculate the mean and median of the sizes of executable binary files on a computer to which you have access. On a Windows system, look at all .exe and .dll files; on a UNIX system look at ... of a page table entry. Assume that all programs are equally likely to be run and thus should be weighted equally.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 3 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 49 (Page No. 260)
Virtual memory provides a mechanism for isolating one process from another. What memory management difficulties would be involved in allowing two operating systems to run concurrently? How might these difficulties be addressed?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 4 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 48 (Page No. 260)
Can you think of any situations where supporting virtual memory would be a bad idea, and what would be gained by not having to support virtual memory? Explain.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 2 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 47 (Page No. 259 - 260)
We consider a program which has the two segments shown below consisting of instructions in segment $0,$ and read/write data in segment $1.$ Segment $0$ has read/execute protection, and segment $1$ has just read/write protection. The ... $1,$ page $4,$ offset $28$ Jump to location in segment $1,$ page $3,$ offset $32$

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 4 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 46 (Page No. 259)
When segmentation and paging are both being used, as in $MULTICS,$ first the segment descriptor must be looked up, then the page descriptor. Does the $TLB$ also work this way, with two levels of lookup?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 2 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 45 (Page No. 259)
Explain the difference between internal fragmentation and external fragmentation. Which one occurs in paging systems? Which one occurs in systems using pure segmentation?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 9 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 44 (Page No. 259)
A machine-language instruction to load a $32-bit$ word into a register contains the $32-bit$ address of the word to be loaded. What is the maximum number of page faults this instruction can cause?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 5 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 43 (Page No. 259)
A group of operating system designers for the Frugal Computer Company are thinking about ways to reduce the amount of backing store needed in their new operating system. The head guru has just suggested not bothering to save the ... this idea work for the program text? Under what conditions, if any, does it work for the data?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 3 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 42 (Page No. 259)
It has been observed that the number of instructions executed between page faults is directly proportional to the number of page frames allocated to a program. If the available memory is doubled, the mean interval between page faults ... page faults, how long would it take to run if twice as much memory were available?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 4 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 41 (Page No. 259)
A computer provides each process with $65,536$ bytes of address space divided into pages of $4096$ bytes each. A particular program has a text size of $32,768$ bytes, a data size of $16,386$ bytes, and a stack size of ... it then fit? Each page must contain either text, data, or stack, not a mixture of two or three of them.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 6 views

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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?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 3 views

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Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 39 (Page No. 259)
You have been hired by a cloud computing company that deploys thousands of servers at each of its data centers. They have recently heard that it would be worthwhile to handle a page fault at server A by reading ... local disk drive. How could that be done? Under what conditions would the approach be worthwhile? Be feasible?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 2 views

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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;

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 2 views

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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?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 5 views

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20

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?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 6 views

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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.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 6 views

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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.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 5 views

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23

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.)

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 6 views

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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 $\tau = 1000?$

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 11 views

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25

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 $0, 1, 2, 3.$

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 6 views

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26

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.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 4 views

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27

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?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 4 views

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28

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.$

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 4 views

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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.

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 4 views

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30

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?

asked Oct 26 in Operating System by Lakshman Patel RJIT Veteran (54.7k points) | 6 views

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