Doubt in LFU Page Replacement

Question

Q : One doubt that I feel while solving the LFU page replacement is that is it like we consider the number of times each page has been referenced till the current page reference in the reference string and then we replace that page which is least frequently occuring or do we count the number of times the page is referenced overall in the reference string later use this count value for page replacement purpose?

In short I want to ask whether we maintain a global counter of page references or counter of each type of page references till the current page reference in the reference string?Plz someone resolve this doubt.

Answer 1

 we consider the number of times each page has been referenced till the current page reference in the reference string and then we replace that page which is least frequently occured.

see this video u will understand clerly

https://www.youtube.com/watch?v=ECAGOfeKU5I