Working Set Page Replacement
	• In practice, convert references into time – E.g. 100ns/ref, 100,000 references  10msec • WS algorithm in practice – On each clock tick all R bits are cleared and record process virtual time t – When looking for eviction candidates, scan all the process’s pages in memory • If R == 1 Store t in LTU of PTE and clear R • If R == 0 If (t – LTU) > WS_Interval , evict the page (not in WS) Else select page with the largest difference