Question 1

With demand paging,if there are no empty page frames available,to move in a new page,one of the current resident pages must be placed into main memory.

Accepted Answer

With demand paging, if there are no empty page frames available, one of the current resident pages must be swapped out to disk (not placed into main memory) to make room for the new page.

Question 2

Demand paging introduced the concept of loading only a part of the program into memory for processing

Accepted Answer

Demand paging is a memory management technique that loads only a part of a program into memory for processing, thereby conserving memory space. When other parts of the program are required, they are loaded into memory on demand.

Question 3

In a demand paging scheme,the first-in first-out (FIFO)page replacement policy chooses the page least recently accessed to be swapped out.

Accepted Answer

In a demand paging scheme, the FIFO page replacement policy chooses the page that has been in memory the longest, not the one least recently accessed, to be swapped out.

Question 4

The optimal selection of cache size and replacement algorithm can result in 80 to 90 percent of all requests being in the cache.

Accepted Answer

Proper selection of cache size and replacement algorithm can significantly increase the cache hit rate, resulting in 80 to 90 percent of requests being served from the cache.

Question 5

Paged memory allocation offers the advantage that it doesn't require the entire job to be stored in memory during its execution.

Accepted Answer

The answer of Paged memory allocation offers the advantage that...

Question 6

The segmented/demand paged memory allocation scheme is a combination of segmentation and demand paging,and it offers the logical benefits of segmentation,as well as the physical benefits of paging.

Accepted Answer

The statement accurately describes the segmented/demand paged memory allocation scheme.

Question 7

With segmented memory allocation,each job is divided into several segments of the same size,one for each module containing pieces that perform related functions.

Accepted Answer

In segmented memory allocation, each job is divided into segments of different sizes, not necessarily the same size, based on the logical divisions of the program, such as modules or functions, rather than a fixed size.

Question 8

The primary advantage of storing programs in noncontiguous page frames (in a paged memory allocation scheme)is that main memory is used more efficiently because an empty page frame can be used by any page of any job.

Accepted Answer

When programs are stored in noncontiguous page frames, any empty page frame can be used by any page of any job, which means that main memory is used more efficiently. This is because there are no wasted or idle page frames that cannot be used by any program. Therefore, the statement is true.

Question 9

Associative memory is a name given to several hardware registers that are allocated to each active job whose task is to associate segment and page numbers belonging to the job being processed with their main memory addresses.

Accepted Answer

This definition is correct and describes the purpose and function of associative memory registers in computer systems.

Question 10

A job's working set is the collection of pages that must be loaded from secondary storage.

Accepted Answer

The answer of A job's working set is the collection...

Question 11

The key to the successful implementation of demand paging is the use of a high-speed CPU.

Accepted Answer

While a high-speed CPU can certainly improve the performance of demand paging, it is not the only key to successful implementation. Other important factors include efficient algorithms for page replacement and memory management, appropriate hardware support, and effective use of storage devices such as hard disks.

Question 12

With demand paging,three additional fields are introduced for each page in each PMT: one to determine if the page being requested is already in memory,a second to determine if the page contents have been modified while in memory,and a third to determine if the page has been referenced most recently.

Accepted Answer

Demand paging involves maintaining additional fields in the page table, including a valid/invalid bit to indicate whether the page is in memory or not, a dirty bit to indicate whether the page contents have been modified while in memory, and a reference bit to determine if the page has been accessed recently. Therefore, the statement is true.

Question 13

Thrashing is a problem that occurs when there are a large number of jobs and many free pages so that pages are being moved around too much.

Accepted Answer

Thrashing occurs when there are too many jobs and too little memory, causing excessive paging and movement of pages between RAM and disk. It is not caused by having many free pages.

Question 14

When using a FIFO scheme,adding more memory always results in better performance.

Accepted Answer

While adding more memory can improve performance in many cases by reducing the number of page faults, it does not always result in better performance due to the Belady's anomaly, where increasing the number of page frames can lead to an increase in the number of page faults under certain conditions, particularly in a FIFO (First In, First Out) page replacement scheme.

Question 15

In the bit-shifting variation of the LRU page replacement policy,the process of shifting bits to the right and resetting the leftmost bit to 1 when a page is referenced gives a history of each page's usage.

Accepted Answer

The bit-shifting variation of the LRU page replacement policy keeps track of the usage history of each page by shifting bits to the right and setting the leftmost bit to 1 whenever a page is accessed. This allows the system to determine which pages have been most recently used and which ones have not been used in a while, making it easier to decide which page to evict when necessary.

Question 16

In a paged memory allocation scheme,to find the actual position of an instruction in memory,first the page number and displacement are determined.Then the operating system refers to the job's PMT to correlate the page with its page frame.

Accepted Answer

This is the correct process in a paged memory allocation scheme.

Question 17

Virtual memory can be implemented with both paging and segmentation.

Accepted Answer

Virtual memory can be implemented with both paging and segmentation. Paging divides memory into equal sized pages, while segmentation divides memory into logical segments. Both techniques can be used to allocate memory in virtual memory systems.

Question 18

A variation of the LRU page replacement algorithm known as the clock page replacement policy is implemented using a pointer to step through the reference bits of the active pages,simulating a clockwise motion.

Accepted Answer

This statement accurately describes the clock page replacement policy as a variation of the LRU algorithm where a pointer is used to step through reference bits in a clockwise direction.

Question 19

Cache memory is based on the concept of using a large,fast,and expensive memory to supplement the workings of main memory.

Accepted Answer

Cache memory is indeed faster and more expensive per byte than main memory, but it is typically much smaller, not larger, in size. Its purpose is to speed up access to frequently used data and instructions by storing them closer to the CPU.

Question 20

The Job Table (JT)contains two values for each active job: the size of the job and the memory location where its Page Map Table is stored.

Accepted Answer

The Job Table contains two values for each active job: the size of the job and the starting memory location where the job is stored. It does not contain the memory location of the Page Map Table.

Quiz 3: Memory Management: Virtual Memory Systems