Cache

computer-architecture memory

Definition

Cache

A cache is a small, fast memory that stores copies of recently or frequently used data from a larger, slower memory.

Its purpose is to reduce the average memory access time by serving many accesses faster than main memory.

In a memory system, caches sit between the processor and main memory.

Terminology

Capacity

The capacity of a cache is the number of data bytes it can store.

Block Size

The block size is the number of bytes brought into the cache at once when a block is fetched from lower memory.

Number of Blocks

The number of blocks is the total number of cache blocks.

Degree of Associativity

The degree of associativity is the number of blocks in one set. An -way set-associative cache therefore stores blocks per set.

Number of Sets

The number of sets is the number of cache sets. Each memory address maps to exactly one cache set.