Why set-associative caches?
Cons
- The higher the associativity the larger the number of comparisons to be made in parallel for high-performance (can have an impact on cycle time for on-chip caches)
- Higher associativity requires a wider tag array (minimal impact)
Pros
- Better hit ratio
- Great improvement from 1 to 2, less from 2 to 4, minimal after that
- Allows parallel search of TLB and caches for larger (but still small) caches (see later)