L2 cache memory

Question

What's the difference between 2*512 KB L2 cache and 1 MB L2 cache?

Answer 1

First one could be dedicated for dual core, 512 KB each core and the second could be shared, if more than one core?

Answer 2

Assuming we are talking about a 2-core processor, they could be two design choices for the second level of the memory hierarchy:

• 2*512 KB L2 cache: two private L2-caches.
• 1 MB L2 cache: L2-cache shared between the two cores.

For example, private L2 caches can be found at the processors of the Sandy Bridge or the K10 microarchitectures. Shared L2 caches can be found at the T1, T2 and T3 UltraSPARC processors (T4 has dedicated L2 caches).