Q59,Paper 3, J1 3. A job has four pages A, B, C, D and the main memory has two page frames only. The job needs to process its pages in following order : ABACABDBACD .Assuming that a page interrupt occurs when a new page is brought in the main memory, irrespective of whether the page is swapped out or not. The number of page interrupts in FIFO and LRU page replacement algorithms are

(A) 9 and 7

(B) 7 and 6

(C) 9 and 8

(D) 8 and 6

Answer C.

Explanation.

Order of pages. ABACABDBACD.

	FIFO(Frame)	Count of page fault	LRU(least recently used frame)	Count of page fault.
A	a	1	a	1
B	ab	2	ab	2
A	ab	2	ab	2
C	bc	3	ac	3
A	ca	4	ac	3
B	ab	5	ab	4
D.	bd	6	ad	5
B	bd	6	ab	6
A	da	7	ab	6
C	ac	8	ac	7
d	cd	9	ad	8