Demand Paging

Question

Assume we have a demand-paged memory. The page table is held in registers. It takes 8 ms to service a page fault if an empty page is available or the replaced page is not modified , and 20 ms if the replaced page is modified. Memory access time is 100 ns . Assume that the page to be replaced is modified 70 % of the time. What is the maximum acceptable page fault rate for an effective access time of no more than 200 ns ?

a) 6.1 * 10 ^ - 6

b) 7.3 * 10 ^ - 6

c) 3.4 * 10 ^ - 4

d) None of these

Comments

Avg time = Page Fault % ( Modified %( Time ) +  (1- Modified %) (Time)) + (1- Page Fault %) Memory time

200 ns = P( 0.7 * 20 ms + 0.30 * 8 ms) + (1-P) 100 ns

Find P?

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Anyone can help me to make c program on above question?

Its a urgent please.

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This year this question was asked in JNUEE-May2019-50 P.hd entrance examination.

Answer 1

OPTION A Correct.

Comments

Why are we not considering the page fault service time required for an empty frame.

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In Question :
"It takes 8 ms to service a page fault if an empty page is available OR the replaced page is not modified".

for Both, service time is same.