Linux uses an LRU algorithm to manage memory. Suppose there is another page repl
ID: 3770794 • Letter: L
Question
Linux uses an LRU algorithm to manage memory. Suppose there is another page replacement algorithm called not frequently used (NFU) that gives each page its own counter that is incremented with each clock cycle. In this way, each counter tracks the frequency of page use, and the page with the lowest counter is swapped out when paging is necessary. In your opinion, how do these two algorithms (LRU and NFU) compare? Explain which one would work best under normal use, and define how you perceive “normal use.”
Explanation / Answer
Least recently used (LRU) algorithm:
The least recently used (LRU) algorithm is a page replacement policy, which is based on the principle “When a page has to be replaced, choose the page which is not used for the long time.
The operating system maintains the stack of reference for each page.
Not frequently used (NFU) algorithm:
In, not frequently used (NFU) page replacement algorithm, a counter is maintained for every page and the counter is initially set to 0.
In each clock cycle, the page counter is incremented by 1.
The counter keeps track of the page usage frequency.
When a page has to be replaced, the page, which is having lowest counter value is swapped.
Comparison of Frequently Used algorithm with Least Recently Used algorithm:
The Not Frequently Used keeps the track of the frequency of the use but it did not track the amount of the recent use.
If any page heavily used at the first time and it is not needed again for a particular time that will get the favor.
If any page is newly loaded and it is used lightly then it will not get focused because it is having low frequency counter value.
Best work algorithm in a normal use:
In most cases the least recently used (LRU) algorithm is preferable in the normal use.
The least recently used algorithm will have the pages which are frequently used.
Usually the user need the files which are recently used.
Perceive of normal use:
The term “normal use” refers to the usual usage of the page file without a special purpose.
The maximum time accessed page requires special type of page replacement policy.
Normally many users want to refer the recently used files only not for maximum time accessed files.
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