FIFO page replacement

This is the easiest page replacement algorithm. Here the 1^st page toward the inside is the 1^st to leave that is the oldest page leaves. To execute this we use a queue and the page at the head of the queue is the one being removed. The new page is put-in at the tail of the queue. The drawback is that its performance is not always good. 

Example Consider a three frame memory and if the sequence in which pages come into the memory is 1, 2,3,4,1 then 1, 2, 3 are entered into the memory in-order. When the page 4 is required after that 1 is removed and the new page 4 is inserted at the tail end with the head being 2. Now if 1 comes after that 2 is removed as it is the new head.