Belady's anomaly


#1

Which of the following page reference strings exhibits Belady’s Anomaly?
a) 1, 2, 3, 5, 3, 2, 5, 2
b) 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5
c) 7, 5, 4, 6, 8, 5, 4, 8
d)None of these

belady’s anomaly means max no. of page fault??


#2

Belady’s anomaly occurs only in case of FIFO.
FIFO shows belady’s anomaly because it doesn’t obey STACK property.

STACK PROPERTY:
Pages(‘m frames’) are subset or equal to Pages(‘m+1 frames’)

You can explore more about it. But remembering this is enough also.

Coming to this question, here you have not specified the frame length. So you have to randomly assume frame size and then see if increasing the frame size increases the number of page faults. If yes then that sequence would exhibit Belady’'s anomaly.