UGC NET CSE | June 2009 | Part 2 | Question: 19

Question

Suppose it takes $100$ ns to access a page table and $20$ ns to access associative memory with a $90$% hit rate, the average access time equals :

• A. $28$       
• B. $20$       
• C. $90$      
• D. $100$

Comments

28??

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shouldn't it be .9 x 20 + .1 x 120

 

as we are going to look at page table after looking in TLB and founding nothing there.

Answer 1

access time = time for associative memory * hit ratio + time for main memory 
= 20*0.9 + 100(1-0.9)
=28ns
 

Comments

shouldn't it be .9 x 20 + .1 x 120

 

as we are going to look at page table after looking in TLB and founding nothing there.