MadeEasy_subject_test_CO

Question

 

How to solve this type of question ?

I didn't get the base concept

 

Comments

if block found in L1 // Hit ratio of L1: 0.75 
{ access block from L1 //hit time of L1: 1 cycle 
} 

else goto L2 //miss ratio of L1: 0.25 
{ 
    if block found in L2 //hit ratio of L2: 0.6
       { access L2 + bring this block from L2 to L1 and then access from L1 
   //Hit time of L2+ hit time of L1= 10+1=11 cycles
       } 
   else goto L3 //miss ratio of L2: 0.4
       {
           if block found in L3 //hit ratio of L3: 0.94 
           { access L3 + bring this block to L2 and then to L1 and then access from L1 
           //hit time of (L3+L2+L1) = 50+10+1=61 cycles 
           } 
           else goto MM //miss ratio of L3: 0.06
           { access the block in MM+bring it to L3 + then to L2+then to L1 
           //Hit time of (MM+L3+L2+L1)=(100+50+10+1)=161 cycles 
           }
        }
          
}

 

So time taken is :

hit_in_L1(time to access L1) +

miss_in_L1 [ hit_in_L2(time to access L1+L2) +

miss_in_L2{ hit_in_L3(time to access L3+L2+L1) +

miss_in_L3(time to access MM+L3+L2+L1)

}

  ]

=0.75*1 + 0.25 [ 0.6(11) +  0.4{ 0.94(61) +0.06 (161) }  ] =9.1

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