A computer system which supports 16 way set associative cache of 256 MB with a block size of 8 bytes. CPU support 32-bit address to access the data. Each tag contains 1 valid bit and 1 replacement bit. How much space is required in the cache controller to store the tag information?
(A) 30 MB
(B) 40 MB
(C) 50 MB
(D) None of these


Answer: (B)

Explanation: According to given data, instruction size is 32 bits, word size is 8 byte (= 23), cache size 256 MB (= 228), and 16 sets (= 24).
So,
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Therefore, tag memory size

= S * P * tag bits
= 221 * 16 * (8 + 1 valid bit + 1 replacement)
= 10 * 225 
= 320 M bits
= 40 MB  

So, option (B) is correct.

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  • Last Updated : 22 Nov, 2018

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