Why Caching Works

Memory hierarchy exploits program locality

• Programs tend to reference parts of their address space that are local in $\text{time}$ and $\text{space}$

Temporal Locality

Recently referenced addressed are likely to be referenced again - reused

Spatial Locality

If a memory address is referenced, nearby addresses are likely to be referenced soon

• E.g. access to array $A[1]$ is likely to be followed by an access to $A[2]$