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The virtual memory system uses the demand paging for its implementation. The probability of getting page faults is $0.25$, the normal memory access time is $200$ nanoseconds. If it takes $2$ millseconds to service a page fault, then what is effective memory access time?

1. $500000$ ns
2. $500075$ ns
3. $500150$ ns
4. $500250$ ns

E.M.A.T. = (1 - p) * ma + p * page fault service time     ,   where p = page fault rate
EMAT = [ 0.75 * 200  + 0.25 * 2000000 ]ns =  500150 n.s
by

yes,  we consider memory access time .

in this formula Effective Memory Access Time

= (1 - p) * ma + p * page fault service time

we use memory access time as ma .

Sir,

We should use hierarchical  approach

as page fault service time to move page from disk to memory and update page table,

after that again memory reference takes place.

For those who are confused about which formula to use.

https://gateoverflow.in/41917/confusion-in-effective-memory-access

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