Belady’s Anomaly in Page Replacement Algorithms

Belady’s anomaly –

Belady’s anomaly says the total number of frames increase, the number of page faults decreases.  While using the First in First Out (FIFO) page replacement algorithm.  However, for FIFO there are cases where this technique fails. This is called Belady’s anomaly.
 For example, if we consider reference string 1,2,3,4,1,2,5,1,2,3,4,5 using 3 Frames, we get 9 total page faults, but if we increase Frames to 4, we get 10 page faults.
Belady's Anomaly in OS

                                                           

Belady's Anomaly in OS

                                                             

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