Page tables are stored in memory , which has access time of 100 ns. The TLB holding 8 page table entries, has an access time of 10 ns. Using execution of process , it is found that 85 % of the time, a required page table entry exist in TLB and only 2 % of the total references causes page fault. Page replacement time is 2 ms . Calculate the effective memory access time , assuming page memory access requires 2 memory accesses and TLB requires one memory access.
A) 38120 ns B) 40000 ns C) 40120 ns D) None
85% time there will be a TLB hit so it will take (10+100) ns.
15% of the time two things can happen:
Page fault occurs 2% of the total memory accesses so X% of 15 should be equal to 2.
i.e. 15 * X/100 = 2 X=200/15.
how 13/15 comes in your equation?