CBSE NET
Q. In a
demand paging memory system, page table is held in registers. The time taken to
service a page fault is 8 m.sec. if an empty frame is available or if the
replaced page is not modified, and it takes 20 m.secs., if the replaced page is
modified. What is the average access time to service a page fault assuming that
the page to be replaced is modified 70% of the time ?
(A) 11.6 m.sec.
(B) 16.4 m.sec.
(C) 28 m.sec.
(D) 14 m.sec
Ans: (B)
Explanation: Let
number of page faults be 100. In which 30 page faults are without modification
so time is 30x8=240 m.sec. And rest
70 page faults are with modification so time is 20x70=1400 m.sec.
Average access time of servicing a page fault is (240+1400)/100=28 m.sec.