= Solution
\b[Use LRU replacement, or a modest recency-based approximation, for eligible buffer-cache entries.] Unlike individual memory accesses, <buffer cache> lookups already pass through <operating system> code. Updating an <LRU replacement> list on each lookup is therefore practical: remove the accessed entry from its old position and put it at the most-recent end; choose the oldest unpinned entry as victim. A hash lookup plus a doubly linked recency list makes this bookkeeping constant time.
Good <temporal locality> favors retaining recently used blocks. <FIFO page replacement>'s arrival-only criterion can evict a block used moments ago. <CLOCK page replacement> can save bookkeeping, but the difficulty of observing arbitrary memory references that motivates it is absent for software-mediated block accesses. Dirty victims require write-back, so a policy can favor an old clean buffer or arrange background cleaning without discarding recent hot data. A long one-pass scan can pollute pure <LRU replacement>; scan-resistant variants are useful refinements rather than a reason to ignore recency altogether.
Back to article page
