Consider a demand-paging system with a paging disk that has an average access an

Question

Consider a demand-paging system with a paging disk that has an average access and transfer time of 20 milliseconds. Addresses are translated through a page table in main memory, with an access time of 1 microsecond per memory access. Thus, each memory reference through the page table takes two accesses. To improve this time, we have added an associative memory that reduces access time to one memory reference if the page-table entry is in the associative memory. Assume that 70 percent of the accesses are in the associative memory and that, of those remaining, 10 percent (or 3 percent of the total) cause page faults. What is the effective memory access time?

Explanation / Answer

Answer:

Given transfer time is =20 milliseconds
access time =1 microsecond
% of accessess are in associative memory =70% = 0.7
% of total taken=3%=0.03

Therefore access Time = (0.7) * (1 microsecond) + (0.18) * (2 microsecond) + (0.03) * (20002 microsecond)

= 601.2 microsecond
= 0.6 millisecond

Hope you will satisfy with my answer Thank you.

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