SSC-IMD-2017-10

Question

The two methods how LRU page replacement policy can be implemented in hardware are :

1) Counters
2) RAM & Registers
3) Stack & Counters
4) Registers

Answer 1

Answer is 3) Stack & Counters 

(A) Counter implementation: Every page entry has a counter. Every time a page is referenced, increment a global counter and store it on the page counter. For page replacement, select the page with the lowest counter 
(B) Stack implementation: Maintain a stack of page number. Move a referenced page to the top. For page replacement, take the page at bottom of stack.