Write through Cache

Question

i'm not getting ans

Comments

It is because you have sense.

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Just forget this question and see this:

http://web.cs.iastate.edu/~prabhu/Tutorial/CACHE/interac.html#diagram

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When they have already said that there are 200 memory references, how come all the options show less than 200 as the number of memory references ?

Answer 1

I do not know how bad they can form a question like this.

Write-through cache - main memory is updated whenever a write happens. Does, the corresponding line brought to cache - depends on write allocate or not, but by default it is assumed not.

"word in the cache" - may be ME invention. Assuming memory is word addressible. So, each memory reference takes 8 bytes.

Also, "dirty bit" should not have been in question.

Average memory references for read = hit rate * 0 + miss rate * line size

$=0.1\times 8 = 0.8$

Average memory references for write = 8 (all write operations goes to memory and only the word is written).

So, total memory reference considering both read and writes

$= 168 \times 0.8 + 32 \times 8 = 134.4 + 256 = 390.4$

Comments

exactly sir!! i got this only

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Average memory references for read = hit rate * 0 + miss rate * line size

=0.1×8=0.8

sir,line size is 128 bytes,why have you taken 8 here then?