Q3. Explain Least Frequently Used (LFU) Page-Replacement Algorithm.
Ans. The least frequently used (LFU) page-replacement algorithm requiresthat the page with the smallest count be replaced. The reason for thisselection is that an actively used page should have a large reference count.A problem arises, however, when a page is used heavily during the initialphase of a process but then is never used again. Since it was used heavily,it has a large count and remains in memory even though it is no longerneeded. One solution is to shift the counts right by 1 bit at regular intervals,forming an exponentially decaying average usage count.