Cache Average access time

Question

So as we know there are 2 different approaches for cache..

Sequential and the Hierarchical.

Exactly which formula should I use when only access times and hit ratio is mentioned in case of 2 level memory system..?

It would be great if someone explains how to approach questions related to average access time.

Comments

following

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What do you mean?

Answer 1

There are 2 ways of accessing the memory, one being simultaneous memory access and the other being hierarchical.

Simultaneous--> T(avg) = H1 T1 + (1-H1) T2

Hierarchical--> T(avg) = H1 T1 + (1-H1) (T2+T1)

When nothing is mentioned we will use Hierarchical by default as it helps in better spatial locality by bringing an entire block in the cache.