FIFO page replacement

This is the easiest page replacement algorithm. At this juncture the 1^st page entering 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 disadvantage is that its performance isn't 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. While the page 4 is required then 1 is removed as well as the new page 4 is inserted at the tail end with the head being 2. Now if 1 comes then 2 is detached as it is the new head.