NOTE
Cache Replacement Policies
LRU, LFU, FIFO, random and modern approximate policies, with workload-dependent hit-rate trade-offs.
This is a historical learning note and may contain outdated or incomplete understanding.
When a bounded cache is full, an eviction policy chooses what to remove.
- LRU favors recent reuse;
- LFU favors frequently reused items;
- FIFO is simple but ignores reuse;
- random can be cheap and surprisingly competitive;
- production caches often use approximate/admission-aware hybrids.
No policy dominates every workload. Capacity, object size, scan resistance, metadata overhead, TTL, and access distribution determine hit rate and latency.