Question $4$

Suppose your cache system has three level caches and here is the system$$s properties:

Size

Miss Rate

Hit Time $($cycle$)$

L$1$ cache

$10$KiB

$20\%($local miss$)$

$1$

L$2$ cache

$100$KiB

$40\%($local miss$)$

$5$

L$3$ cache

$1$MiB

$5\%($global miss$)$

$10$

Main Memory

$4$GiB

$0\%$

$100$

Hint:

Local miss rates refer to the percentage of accesses reaching that level cache that miss in that cache $($i$.$e$.,$ if the local miss rate for L$2$ cache is $50\%,$ then half of the accesses that reach the L$2$ cache miss in the L$2$ cache$)$

Global miss rates refer to the percentage of total accesses that miss at that level cache $($i$.$e$.,$ if the global miss rate for L$2$ cache is $50\%,$ then half of all memory accesses miss in the L$2$ cache$)$

Flag question: Question $12$

Question $121$ pts

Question $4\mathrm{.}1$

What is the percentage of total accesses that hit in the L$2$ cache?

Hint:

It might be easier to think about this problem in terms of a fraction of $100$ total accesses

Group of answer choices

$12\%$

$10\%$

$11\%$

$13\%$

Flag question: Question $13$

Question $131$ pts

Question $4\mathrm{.}2$

What is the percentage of total accesses that hit in the L$3$ cache?

Group of answer choices

$3\%$

$4\%$

$5\%$

$6\%$

Flag question: Question $14$

Question $141$ pts

Question $4\mathrm{.}3$

What is the AMAT of this memory hierarchy?

Hint:

AMAT $=$ Cycles to access L$1+$ additional cycles to access L$2*$ fraction of total accesses reaching L$2+$ additional cycles to access L$3*$ fraction of total accesses reaching L$3+$ additional cycles to access main memory $*$ fraction of total accesses reaching main memory