GATE - 2007 | OS | The address sequence generated by tracing a particular program

GATE - 2007 [Operating System]

Question:

The address sequence generated by tracing a particular program executing in a pure demand paging system with 100 bytes per page is 0100, 0200, 0430, 0499, 0510, 0530, 0560, 0120, 0220, 0240, 0260, 0320, 0410. Suppose that the memory can store only one page and if x is the address which causes a page fault then the bytes from addresses x to x + 99 are loaded on to the memory. How many page faults will occur ?  

A	0
B	4
C	7
D	8

     

Solution:

Option (C) is Correct.

0100 - Page fault, address till 199 in memory
0200 - Page fault, address till 299 in memory
0430 - Page fault, address till 529 in memory
0499 - No page fault
0510 - No page fault
0530 - Page fault, address till 629 in memory
0560 - No page fault.
0120 - Page fault, address till 219 in memory
0220 - Page fault, address till 319 in memory
0240 - No page fault
0260 - No page fault
0320 - Page fault, address till 419 in memory
0410 - No page fault
So, total page faults = 7.

Thank You