UGC NET CSE | October 2020 | Part 2 | Question: 15

Question

Consider a hypothetical machine with $3$ pages of physical memory, $5$ pages of virtual memory, and $<A, B, C, D, A, B, E, A, B, C, D, E, B, A, B>$ as the stream of page reference by an application. If $P$ and $Q$ are the number of page faults that the application would incur with FIFO and LRU page replacement algorithms respectively, then $(P,Q)=$ _______(Assuming enough space for storing $3$ page frames)

• A. $(11,10)$
• B. $(12,11)$
• C. $(10,11)$
• D. $(11,12)$

Comments

3 pages in a frame .FIFO :  A ,B ,C ,D  ,A ,B ,E, C ,D ,B,A   total : 11

LRU :  A ,B ,C ,D  ,A ,B ,E, C ,D ,E,B,A total : 12

hence option D (11,12) IS CORRECT.

Answer 1

3 pages of physical memory means 3 frames (so at a time only max 3 page in  frames)

 5 pages of  virtual memory means 5 page

 A B C D A B  E A B C D E B A B

FIFO  Page Fault  for  A ,B ,C ,D  ,A ,B ,E, C ,D ,B,A   TOTAL= 11

LRU   Page Fault  for  A ,B ,C ,D  ,A ,B ,E, C ,D ,E,B,A   TOTAL= 12

Option 4 is the right ans

Comments

5 pages of virtual memory is signifying the pages A, B, C, D, E. Right?

Answer 2

The answer is D option.