Understanding CPU cache and cache line

Question

I am trying to understand how CPU cache is operating. Lets say we have this configuration (as an example).

• Cache size 1024 bytes
• Cache line 32 bytes

Answer 1

1. The cache metadata is typically not counted as a part of the cache itself. It might not even be stored in the same part of the CPU (it could be in another cache, implemented using special CPU registers, etc).
2. This depends on whether your CPU will fetch unaligned addresses. If it will only fetch aligned addresses, then the example you gave would be correct. If the CPU fetches unaligned addresses, then it might fetch the range 0xFFFF0008 to 0xFFFF0027.
3. The index bytes are still useful, even when cache access is aligned. This gives the CPU a shorthand method for referencing a byte within a cache line that it can use in its internal bookkeeping. You could get the same information by knowing the address associated with the cache line and the address associated with the byte, but that's a whole lot more information to carry around.

Different CPUs implement caching very differently. For the best answer to your question, please give some additional details about the particular CPU (type, model, etc) that you are talking about.