Let the page fault service time be 10 ms in a computer with average memory…

2016

Let the page fault service time be 10 ms in a computer with average memory access time being 20 ns. If one page fault is generated for every
106 memory accesses, what is the effective access time for the memory?

  1. A.

    21.4 ns

  2. B.

    29.9 ns

  3. C.

    23.5 ns

  4. D.

    35.1 ns

Attempted by 62 students.

Show answer & explanation

Correct answer: B

The effective access time (EAT) is calculated using the formula EAT = (1 - p) * T_mem + p * T_fault. Given memory access time T_mem = 20 ns, page fault service time T_fault = 10 ms (10^7 ns), and fault rate p = 1/10^6. Substituting these values: EAT ≈ (20 ns) + (10^7 ns * 10^-6) = 20 ns + 10 ns = 30 ns. The closest option is 29.9 ns.

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