What is L1+L3 cache?

The rules are set in something called the inclusion policy. For example, Intel Core processors have fully inclusive L1+L3 cache. This means that the same data in Level 1, for example, can also be in Level 3.

How do I change the size of the L3 cache?

The L3 cache is special memory built into the CPU package. There is no setting anywhere that can change it’s size. Even Intel or AMD could not change this for an existing CPU. There is a registry setting referring to the L2 cache that is sometimes mentioned in Internet articles.

What is Level 3 cache in a CPU?

Level 3 cache, even though it is directly around a single core, is fully shared with the others — each one can freely access the contents of another’s L3 cache. It’s much larger (between 2 and 32 MB) but also a lot slower, averaging over 30 cycles, especially if a core needs to use data that’s in a block of cache some distance away.

What does the L2 cache setting do?

There is a registry setting referring to the L2 cache that is sometimes mentioned in Internet articles. Maybe that is what you are referring to. It’s purpose was to tell Windows the size of the L2 cache which it used to make some minor optimizations.