Set-associative cache is a specific type of cache memory that occurs in RAM and processors. It divides the cache into between two to eight different sets or areas. Data is stored in them all, but the cache distributes it to each set in sequence, rather than randomly. In most cases, data from each set is also read sequentially, speading up the reading process just a little.
Technipages Explains Set-Associative Cache
Because the cache is split though, sets that have been written on and are not in use anymore can be prepped for the next read or write operations, while data is being read from or written to a different set or area. This means that rather than treating the cache as one larger unit that is either active or inactive, several smaller units are created and allow the system more flexibility when it comes to reading and writing.
This design makes it possible for the microprocessor to complete an instruction in one clock cycle, rather than taking longer. More sets and areas mean more performance, but also higher cost when it comes to manufacturing and implementing that memory. The industry-accepted standard and compromise between the two extremes is four areas – this allows the computer to switch between areas at a reasonable speed without driving up the price too far. Being able to assign data to whatever sections are free and suitable makes it easier for the computer to react quickly, without having to specifically look for a spot that can be used.
Common Uses of Set-Associative Cache
- Set-associative cache can be anywhere from 2 sets to eight sets wide.
- The alternative to set-associative caching is called direct mapping – it gives the processor less freedom on where to put things.
- Set-associative caching means that sections not used can be prepped for the next action once one is complete.
Common Misuses of Set-Associative Cache
- Set-associative caching is a process done in the CPU to preserve memory space.