The Gateway to Computer Science Excellence
0 votes

$h_1→L1$ hit ratio 
$h_2→L2$ hit ratio
$C_1→ L1$ access time
$C_2→ $Miss penalty to transfer information from L2 to L1
$M→$ Miss penalty to transfer information from main memory to L2

Average access time given in Carl Hamacher's book is


Shouldn’t it be


where $C_2’\rightarrow$ L2 access time (note that this is different from $C_2$)

When L2 miss occurs, book formula considers only $M$, that is moving data from memory to L2. Isnt this data also moved from L2 to L1 making us add $C_2$? Also $C_2$ and $M$ are duration for moving data from L2 to L1 and memmory to L2 respectively. These are penalties. But before penalties, a miss occurs which requires $C_1$ time for L1 miss and $C_2’$ time for L2 miss. But these does not seem to have added in the book formula. I have added them as highlighted in red.

Is my equation correct or book’s equation. Or something more is going on here, which I am unaware of?

in CO and Architecture by | 320 views
Thats the difference between Simultaneous and Hierarchical cache. Carl Hamacher deals with Simultaneous cache.

Please log in or register to answer this question.

Related questions

Quick search syntax
tags tag:apple
author user:martin
title title:apple
content content:apple
exclude -tag:apple
force match +apple
views views:100
score score:10
answers answers:2
is accepted isaccepted:true
is closed isclosed:true
52,345 questions
60,489 answers
95,297 users