And yet Another Extreme Example: Fully Associative cache

• Fully Associative Cache -- push the set associative idea to its limit!

  • Forget about the Cache Index
  • Compare the Cache Tags of all cache entries in parallel
  • Example: Block Size = 32B blocks, we need N 27-bit comparators

• By definition: Conflict Miss = 0 for a fully associative cache

:

Cache Data

Byte 0

0

4

31

:

Cache Tag (27 bits long)

Valid Bit

:

Byte 1

Byte 31

:

Byte 32

Byte 33

Byte 63

:

Cache Tag

Byte Select

Ex: 0x01

X

X

X

X

X

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