Answer:
Optimal
Time 123456789101112
RS. ecbeagdcegda
F0. eeeeeeeee e e a
F1 c c c c c c c c c c c
F2 b b b g g g g g g g
F3 a a d d d d d d
Page fault? * * * * * * *
Total page fault:7
2. LRU
Time 1 2 3 4 5 6 7 8 9 10 11 12
RS e c b e a g d c e g d a
F0 e e e e e e e c c c c a
F1 c c c c g g g g g g g
F2 b b b b d d d d d d
F3 a a a a e e e e
Page fault? Y Y Y N Y Y Y Y Y N N Y Total page fault:9
3. LRU approximation algorithm: Second chance
Time 1 2 3 4 5 6 7 8 9 10 11 12
RS e c b e a g d c e g d a
F0 0,e 0,e 0,e 1,e 1,e 0,e 0,e 0,e 1,e 1,e 1,e 0,e
F1 0,c 0,c 0,c 0,c 0,g 0,g 0,g 0,g 1,g 1,g 0,g
F20,b0,b0,b0,b0,d0,d0,d0,d1,d0,dF30,a0,a0,a0,c0,c0,c0,c0,a
Page fault? YYYNYYYYNNNY
Total page fault: 8
Answer:
2,970
Explanation:
The string are arranged as follow: a,a,b,b,c,c,d,e,e,g,g,g
There are 12 combinations and with four frames
Then, it can be computed thus: nCr, where n = 12 and r = 4 = n!/r(n - r)!
∴ 12C4 = 12!/4(8)! = 2970
