Test by Bikram | Computer Organization and Architecture | Test 2 | Question: 8

Question

A two-dimensional array int $a [32] [32]$ where each element takes $2$ byte, cache size $2^{12}$  bytes and line size is $2^6$  bytes. The following program segment is stored in the direct mapped cache.

for ( i= 1; i<= 32; ++ i)
for (j= 0; j<= 31; ++ j)
a[i][ j] = 0

If initially cache is empty then total number of compulsory cache miss for storing above array is ________

Comments

This Mock test is really Nice!

Thanks, GO.

Answer 1

It is due total array element size occupy 32*32*2 bytes=$2^{11}$ bytes

where the cache size is $2^{12}$ bytes

Now each cache word size is $2^6$ bytes

so in first $2^{11}$/  $2^6$ references all array items in cache so compulsory misses are = $2^5$ = 32

Comments

@Bikram Sir,

Solution is correct but explanation may not be

it will be accessing 31*32 integers

i=1 and i<=32

but array has range from a[0][0]...a[31][31]

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shldn't this be 2^12/2^6 as here the number of compulsory misses will be total number of blocks since after we bring in the first element of each block for the rest it's a hit..