MOCK TEST

Question

Consider an L1 cache, L2 cache, and main memory. The hit rates and hit times for each are:
70% hit rate, 5 ns hit time for L1.
90% hit rate, 14 ns hit time for L2.
100% hit rate, 150 ns hit time for main memory
If there a total of 300 memory accesses, how many of these accesses are serviced from main memory?

Comments

4110 nsec

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Given solution

Explanation:
L1 miss rate = 1 − 0.7 = 0.3
L2 miss rate = 1-0.90 = 0.1
Out of all 300 memory accesses 30% (90 accesses ) come to L2. From the 90 memory accesses that come to L2 cache, 10% of them (9 accesses) come to main memory. So total no. of memory accesses serviced from main memory = 9.

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yes answer is corrrect i wrote the access time.

yes 9 memory aceess required.

how 0.3(0.1 ) = 0.03 for 1 refference so for 300 *0.03 = 9