Fully-associative cache
Fully-associative cache
Instead of placing memory blocks in specific cache locations based on memory address, in a fully-associative cache, we can allow a block to go anywhere in cache.
A fully-associative cache address is composed of two fields: ?
- the tag field: the block of main memory
- the offset field: the position of the word within the block
In fully-associative caches, we may have to search the entire cache to find a particular tag which is an expensive process. In a direct-mapped cache, the search is fast as there is only one location where a particular address can be stored, so there is no search needed.
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- However, direct-mapped cache is overly rigid. Say the addresses were
000000then110000then000000then110000. In this case, the addresses map to different memory blocks but the same cache block.- We would be constantly removing and adding the same blocks to the cache (thrashing) even though we are only accessing two blocks which is an expensive process.
title: Example 1
title: Example 2
title: Example 3
