CO-Write Through

Question

 my doubt

1) default is hierarchal or simultaneous.

2)will we use hierarchical or simultaneous here..also explain.

Comments

I think until unless they don't mention in the question about the hierarchal access we don't consider it. In terms of hierarchal access following words may be used:- "on the miss in L_i cache the data is transferred from L_i+1 to L_i"

I did:- $0.75 *(0.9*45+0.1*750) + 0.25*750 = 274.125$

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Okay so you considered simultaneous access in case of read operation as well?

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I have considered simultaneous access for "read operation" only because for write you have to employ write-through protocol.

Answer 1

Memory request for read $=0.75$

Memory request for write $=0.25$

Now, it is given for read request $90$% is hit and write through protocol is used.

In write through protocol, cache and main memory updated simultaneously.

 

• So, for Read time required $=0.75(0.9*45+0.1*750)=86.625ns.$

 

• for Write time required (as hit ratio of write is $1$)$=0.25*750=187.5$

Total time required $=86.625+187.5=274.125ns.$