Suppose the time to service a page fault is on the average 10 milliseconds,…

2000

Suppose the time to service a page fault is on the average 10 milliseconds, while a memory access takes 1 microsecond. Then a 99.99% hit ratio results in average memory access time of?

  1. A.

    1.9999 milliseconds

  2. B.

    1 millisecond

  3. C.

    9.999 microseconds

  4. D.

    1.9999 microseconds

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Correct answer: D

The average memory access time (AMAT) formula is AMAT = Hit Ratio × Memory Access Time + Miss Ratio × Page Fault Time. First, convert the page fault time to microseconds: 10 milliseconds equals 10,000 microseconds. The miss ratio is 1 - 0.9999 = 0.0001. Substituting the values gives 0.9999 × 1 + 0.0001 × 10,000 = 0.9999 + 1 = 1.9999 microseconds.

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