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This set of Operating System (OS) Multiple Choice Questions & Answers (MCQs) focuses on Operating System Set 18

Q1 | Virtual memory allows                          
  • execution of a process that may not be completely in memory
  • a program to be smaller than the physical memory
  • a program to be larger than the secondary storage
  • execution of a process without being in physical memory
Q2 | A process is thrashing if                          
  • it is spending more time paging than executing
  • it is spending less time paging than executing
  • page fault occurs
  • swapping can not take place
Q3 | The ability to execute a program that is only partially in memory has benefits like
  • the amount of physical memory cannot put a constraint on the program
  • programs for an extremely large virtual space can be created
  • throughput increases
  • all of the mentioned
Q4 | Virtual memory is normally implemented by                  
  • demand paging
  • buses
  • virtualization
  • all of the mentioned
Q5 | Segment replacement algorithms are more complex than page replacement algorithms because                          
  • segments are better than pages
  • pages are better than segments
  • segments have variable sizes
  • segments have fixed sizes
Q6 | A swapper manipulates                         whereas the pager is concerned with individual                of a process.
  • the entire process, parts
  • all the pages of a process, segments
  • the entire process, pages
  • none of the mentioned
Q7 | Using a pager                          
  • increases the swap time
  • decreases the swap time
  • decreases the swap time & amount of physical memory needed
  • increases the amount of physical memory needed
Q8 | The valid – invalid bit, in this case, when valid indicates?
  • the page is not legal
  • the page is illegal
  • the page is in memory
  • the page is not in memory
Q9 | A page fault occurs when?
  • a page gives inconsistent data
  • a page cannot be accessed due to its absence from memory
  • a page is invisible
  • all of the mentioned
Q10 | When a page fault occurs, the state of the interrupted process is                          
  • disrupted
  • invalid
  • saved
  • none of the mentioned
Q11 | When a process begins execution with no pages in memory?
  • process execution becomes impossible
  • a page fault occurs for every page brought into memory
  • process causes system crash
  • none of the mentioned
Q12 | If the memory access time is denoted by ‘ma’ and ‘p’ is the probability of a page fault (0 <= p <= 1). Then the effective access time for a demand paged memory is
  • p x ma + (1-p) x page fault time
  • ma + page fault time
  • (1-p) x ma + p x page fault time
  • none of the mentioned
Q13 | When the page fault rate is low
  • the turnaround time increases
  • the effective access time increases
  • the effective access time decreases
  • turnaround time & effective access time increases
Q14 | Locality of reference implies that the page reference being made by a process
  • will always be to the page used in the previous page reference
  • is likely to be one of the pages used in the last few page references
  • will always be one of the pages existing in memory
  • will always lead to page faults
Q15 | Which of the following page replacement algorithms suffers from Belady’s Anomaly?
  • optimal replacement
  • lru
  • fifo
  • both optimal replacement and fifo
Q16 | In question 2, if the number of page frames is increased to 4, then the number of page transfers                          
  • decreases
  • increases
  • remains the same
  • none of the mentioned
Q17 | A memory page containing a heavily used variable that was initialized very early and is in constant use is removed, then the page replacement algorithm used is                          
  • lru
  • lfu
  • fifo
  • none of the mentioned
Q18 | Users                that their processes are running on a paged system.
  • are aware
  • are unaware
  • may unaware
  • none of the mentioned
Q19 | If no frames are free,            page transfer(s) is/are required.
  • one
  • two
  • three
  • four
Q20 | A FIFO replacement algorithm associates with each page the                
  • time it was brought into memory
  • size of the page in memory
  • page after and before it
  • all of the mentioned
Q21 | What is the Optimal page – replacement algorithm?
  • replace the page that has not been used for a long time
  • replace the page that has been used for a long time
  • replace the page that will not be used for a long time
  • none of the mentioned
Q22 | LRU page – replacement algorithm associates with each page the              
  • time it was brought into memory
  • the time of that page’s last use
  • page after and before it
  • all of the mentioned
Q23 | What are the two methods of the LRU page replacement policy that can be implemented in hardware?
  • counters
  • ram & registers
  • stack & counters
  • registers
Q24 | When using counters to implement LRU, we replace the page with the                          
  • smallest time value
  • largest time value
  • greatest size
  • none of the mentioned
Q25 | There is a set of page replacement algorithms that can never exhibit Belady’s Anomaly, called                          
  • queue algorithms
  • stack algorithms
  • string algorithms
  • none of the mentioned