How LRU technique is implemented
The LRU policy is more difficult to execute but has been more attractive on the assumption that the least recently used page is a better candidate for removal than the least recently used page is a better candidate for removal than the least recently loaded page as in FIFO. The LRU algorithm can be executed by associating a counter with every page that is in the major memory. When a page is referenced, its associated counter is set to zero. At fixed interval of time, the counters associated with all pages presently in memory are incremented by 1. The least recently used page in the page with the highest count. The counters are often known as aging registers, as their count indicates their age, that is how long ago their associated pages have been referenced.