Memory Hierarchy

There is a rule in the memory world that, the faster you could read and write on it, the smaller its volume for data would be.

Cache in depth

The cache is made up of small chunks of mirrored main memory. The size of these chunks is called the line size, and is typically something like 32 or 64 bytes. So the size of a cache is a multiple of a cache line.

When the processor write data in the cache, it is not instantly wrote into main memory, but suspended. And this kind of cache lines are referred to as dirty.