OS C-21 (UNITS 5 & 6)

 Which of the following is an advantage of virtual memory?

• Processes can be given priority
  

• Programs larger than the physical memory size can be run

• Faster access to memory on an average.

• Linker can assign addresses independent of where the program will be loaded in physical memory.

  Virtual memory be implemented via?    

• Paging

• Logical paging

• Demand paging

• Simple Paging.

Which of the following page replacement algorithms is expensive to implement?

• FIFO

• LRU

• MRU

• LFU

Using LRU algorithm find the number of page faults that occurs when references to the page occur in order 1, 2, 4, 5, 2, 1, 2, 3. Assume that the main memory can accommodate 3 pages and memory already has pages 1 and 2 in it. Page 1 is brought earlier than page 2.

• 2

• 3

• 4

• 5

Thrashing occurs due to

• Decrease in degree of multiprogramming.

• Increase in degree of multiprogramming.

• Increase in size of virtual memory.

• Decrease in size of virtual memory.

Which is true with reference to the working set model for page replacement?   

• It refers to static page replacement algorithm 

• It refers to local page replacement algorithm

• It dynamically provides frames for the process as per its needs

• It increases thrashing

Page fault occurs when

•  When a requested page is in memory

• When a requested page is not in memory

• When a page is corrupted

• When an exception is thrown

In FIFO page replacement algorithm, when a page must be replaced:

• Oldest page is chosen

• newest page is chosen

• Random page is chosen

• none of the mentioned

Thrashing can be avoided if _____

• The pages, belonging to the working set of the program, are in the main memory.

• The speed of I/O is increased.

• The speed of CPU is increased.

• The capacity of memory is decreased.

Belady's Anomaly is a behavior of ___ page replacement algorithm.

•  Optimal

• LRU

• MRU

• FIFO