Cache Memory Part 1

Flashcards covering key terminology and concepts related to Cache Memory.

Cache Memory

Small, fast storage used to improve average access time to slow memory.

Cache Controller

The hardware that controls access to cache or generates requests to memory.

Cache Miss

Occurs when the requested data is not found in the cache.

Hit Rate

Number of memory accesses that find the data in the upper level with respect to the total number of memory accesses.

Miss Rate

Number of memory accesses not finding the data in the upper level with respect to the total number of memory accesses.

Miss Penalty

Time needed to access the lower level and to replace the block in the upper level.

Direct Mapped Cache

A type of cache mapping where each memory block is mapped to exactly one block in the cache.

Associative Cache

A type of cache where a block can be placed in any entry in the cache.

Least Recently Used (LRU)

A replacement policy that chooses the block unused for the longest time.

Write-Through Policy

Writes information to both the block in the cache and to the block in the lower level memory.

Write-Back Policy

Writes information only to the cache and to lower-level memory only when the cache block is replaced.

Valid Bit

Indicates if a cache position contains valid data (Y = valid, N = invalid).

Cache Block Size

The fixed size collection of data retrieved from memory and placed into the cache.

Hit Time

Time to access the data in the upper level of the hierarchy.

Average Memory Access Time (AMAT)

Calculated as AMAT = Hit Rate * Hit Time + Miss Rate * Miss Time.

Cache Tag

Contains the value that uniquely identifies the memory address corresponding to the stored data.

n-way Set Associative Cache

Allows each block to be placed in a fixed number of locations, each containing multiple entries.