Self-Doubt

Question

Consider Main memory M and Cache C.

1. When we say the access time of main memory is T what parameters does it include?Is it

. just obtaining data from M or

.obt data from M and Transfer it to cache(I understood as this)  or

. Obt data from M, Transfer it to cache and read cache again, and transfer it to the Processor

2 When nothing is specified do we assume hierarchical or simultaneous access

3 In case of miss do we always put the data into the cache and again read it from there or do we keep a buffer between Memory and Cache and give it to the processor while the data is being transferred from memory to cache? If nothing is given which scenario do we take?

Pls, help me with these finer aspects. I understood the overall idea. In NATs, I'm missing by small margins.

Comments

@arjun sir can u please verify this

Answer 1

1. It only refers to the time taken to get it from the main memory. Generally, that is what access time means - time taken to get from X (X can be cache, TLB, main memory, hard disk etc.)

2. By default, most computers use a hierarchical memory system  which is - cache, main memory and hard disk. None of the standard books mention a situation where simultaneous access is possible.

3. In case of a miss, the data is brought from the memory to the cache and stored there, and read from there. Afaik, there's no buffer between memory and cache.