WSClock (combines Clock and WS algorithms)
	• WSClock – Circular list of entries containing • R, M, time of last use • R and time are updated on each clock tick – Clock “hand” progresses around list • If R = 1, reset and update time • If R = 0, and if age > WS_interval, and if clean, then claim it. • If R = 0, and if age > WS_interval, and if dirty, then schedule a disk write • Step “hand” to next entry on list • Very common in practice