Clock
Second-chance / CLOCK
Circular scan: if ref=1 clear and advance; if ref=0, evict. Approximates LRU with cheap bits.
IdleStep a query
Clock hand at 0. On access set ref=1. Evict first frame with ref=0 (give second chance if ref=1).
hits 0 · misses 0 · Space / ← →
Clock Cache Replacement