Average access time

Question

Assume memory access time is 10 μs and reading a page from disk takes 10 ms. If page fault occur in 0.5% of the memory references then what is the average memory access time (in μsec)?

Comments

5010microsec?

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not sure, i am getting 59.95 μsec. But answer given is 10 μsec.

Answer 1

Main memory access time (m) = 10 microsec

Service time (ps) = 10 milisec

Page fault rate (p)= 0.5% = 5*10^3

Thus

EMAT= m+p(ps)

           = 10 microsec + 5*10-3*10*10^-3

           = 10 microsec + 5 * 10^-6

           = 10 microsec + 5 microsec

           = 15 microsec