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Thursday, February 20, 2020

Page Replacement


Page Replacement 

While a user process is executing, a page fault occurs. the operating system determines where the desired page is residing on the disk. If there are no free frames on the free frame list, the operating system has several options.

            1. It could terminate the user process; this option is not best choice.
2. Swap some process out of memory completely, freeing up its page frames.
3. Find some page in memory that isn't being used right now, and swap that page only out to disk, freeing up a frame that can be allocated to the process requesting it. This is known as page replacement, and is the most common solution.

There are many different algorithms for page replacement:
a. Basic page replacement
b. FIFO page replacement
c. Optimal page replacement
d. LRU page replacement
e. LRU approximation page replacement
f. Counting based page replacement
g. Page- buffering algorithms
                                                                

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