Clock Replacement (A slight variation of Second Chance)
	• Create circular list of PTEs in FIFO Order • One-handed Clock – pointer starts at oldest page – Algorithm – FIFO, but  check Reference bit • If R == 1, set R = 0 and advance hand • evict first page with R == 0 – Looks like a clock hand sweeping PTE entries – Fast, but worst case may take a lot of time • Two-handed clock – add a 2nd hand that is n PTEs ahead – 2nd hand clears Reference bit – Allows very active pages to stay in longer