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3571

Andrew S. Tanenbaum (OS) Edition 4 Exercise 4 Question 3 (Page No. 333)
In early UNIX systems, executable files (a.out files) began with a very specific magic number, not one chosen at random. These files began with a header, followed by the text and data segments. Why do you think a ... chosen for executable files, whereas other file types had a more-or-less random magic number as the first word?

In early UNIX systems, executable files (a.out files) began with a very specific magic number, not one chosen at random. These files began with a header, followed by the ...

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admin asked Oct 26, 2019

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3572

Andrew S. Tanenbaum (OS) Edition 4 Exercise 4 Question 2 (Page No. 332)
In Windows, when a user double clicks on a file listed by Windows Explorer, a program is run and given that file as a parameter. List two different ways the operating system could know which program to run.

In Windows, when a user double clicks on a file listed by Windows Explorer, a program is run and given that file as a parameter. List two different ways the operating sys...

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admin asked Oct 26, 2019

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3573

Andrew S. Tanenbaum (OS) Edition 4 Exercise 4 Question 1 (Page No. 332)
Give five different path names for the file /etc/passwd. (Hint: Think about the directory entries ‘‘.’’ and ‘‘..’’.)

Give five different path names for the file /etc/passwd. (Hint: Think about the directory entries ‘‘.’’ and ‘‘..’’.)

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admin asked Oct 26, 2019

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3574

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.

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 t...

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admin asked Oct 26, 2019

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3575

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 ...

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admin asked Oct 26, 2019

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3576

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.

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...

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admin asked Oct 26, 2019

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3577

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.

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...

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admin asked Oct 26, 2019

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3578

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.

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 ...

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admin asked Oct 26, 2019

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3579

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.

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 a...

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admin asked Oct 26, 2019

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3580

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?

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...

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admin asked Oct 26, 2019

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3581

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 $32$

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 p...

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admin asked Oct 26, 2019

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3582

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?

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...

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admin asked Oct 26, 2019

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3583

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?

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 t...

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admin asked Oct 26, 2019

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3584

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?

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. ...

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admin asked Oct 26, 2019

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3585

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...

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admin asked Oct 26, 2019

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3586

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?

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 ha...

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admin asked Oct 26, 2019

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3587

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

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3588

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...

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admin asked Oct 26, 2019

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3589

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...

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3590

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...

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admin asked Oct 26, 2019

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3591

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...

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admin asked Oct 26, 2019

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3592

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...

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admin asked Oct 26, 2019

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3593

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?

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admin asked Oct 26, 2019

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3594

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...

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admin asked Oct 26, 2019

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3595

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...

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admin asked Oct 26, 2019

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3596

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?

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 ...

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admin asked Oct 26, 2019

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3597

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 25 (Page No. 256)
A computer with an $8-KB$ page, a $256-KB$ main memory, and a $64-GB$ virtual address space uses an inverted page table to implement its virtual memory. How big should the hash table be to ensure a mean hash chain length of less than $1?$ Assume that the hash table size is a power of two.

A computer with an $8-KB$ page, a $256-KB$ main memory, and a $64-GB$ virtual address space uses an inverted page table to implement its virtual memory. How big should th...

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admin asked Oct 26, 2019

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3598

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 23 (Page No. 256)
How can the associative memory device needed for a $TLB$ be implemented in hardware, and what are the implications of such a design for expandability?

How can the associative memory device needed for a $TLB$ be implemented in hardware, and what are the implications of such a design for expandability?

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admin asked Oct 26, 2019

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3599

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 21 (Page No. 256)
Below is an execution trace of a program fragment for a computer with $512-byte$ pages. The program is located at address $1020,$ and its stack pointer is at $8192\:\:($the stack grows toward $0).$ Give the ... $16$ from the stack pointer Compare the actual parameter to the immediate constant $4$ Jump if equal to $5152$

Below is an execution trace of a program fragment for a computer with $512-byte$ pages. The program is located at address $1020,$ and its stack pointer is at $8192\:\:($t...

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admin asked Oct 26, 2019

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3600

Andrew S. Tanenbaum (OS) Edition 4 Exercise 3 Question 18 (Page No. 256)
Section $3.3.4$ states that the Pentium Pro extended each entry in the page table hierarchy to $64$ bits but still could only address only $4\: GB$ of memory. Explain how this statement can be true when page table entries have $64$ bits.

Section $3.3.4$ states that the Pentium Pro extended each entry in the page table hierarchy to $64$ bits but still could only address only $4\: GB$ of memory. Explain how...

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admin asked Oct 26, 2019

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