Which of the following page replacement algorithms can exhibit Belady’s Anomaly ?
First-In, First-Out (FIFO)
Belady's Anomaly is the counter-intuitive situation in which giving a process more page frames actually produces more page faults. It appears only in FIFO page replacement.
The reason lies in what FIFO uses to choose a victim. FIFO evicts whichever page arrived earliest, which has nothing to do with whether that page is about to be needed again. Because the set of pages FIFO keeps with three frames is not guaranteed to be a subset of what it keeps with four, adding a frame can change the eviction order for the worse. The classic reference string 1, 2, 3, 4, 1, 2, 5, 1, 2, 3, 4, 5 gives nine faults with three frames but ten with four.
The other algorithms are immune because they are stack algorithms: the pages held with \(n\) frames are always a subset of those held with \(n+1\) frames, so faults can never increase when frames are added. LRU chooses by least recent use, MRU by most recent use, and OPT by the furthest future reference.
Hence, the answer is First-In, First-Out (FIFO).
Important Questions from Operating Systems
Active portion contains an operating system that will be loaded
Which of the following statement(s) is/are true about control unit?
I. It manages and coordinate the entire computer system
II. It does not perform any actual processing on data
A collection of software that manages computer hardware resources and provides common services for computer programs is
_____ runs on the computer hardware and serve as a platform for other software.
In the context of computers, what is Ubuntu?
