GATE IT 2008 | Question: 16

Question

A paging scheme uses a Translation Look-aside Buffer (TLB). A TLB-access takes $10$ ns and the main memory access takes $50$ ns. What is the effective access time(in ns) if the TLB hit ratio is $\text{90%}$ and there is no page-fault?

• A. $54$
• B. $60$
• C. $65$
• D. $75$

Comments

Good question to keep in short notes.

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We always need to have 1 TLB and 1 MM access (to get frame from MM), when there is miss we need to have 1 extra MM access (to get page table).

So EMT = 10 + 50 + 0.1(50) = 55ns

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no @smsubham its not like that . if its a hit then you need to access TLB and main memory once but if its a miss then you have already accessed TLB which didnt turn out to be worthy so u need to access main memory twice (once for the page table and second time for the data).

Answer 1

"there is no page-fault"  means we should just put

10ns + 50ns =60 ns

Comments

thank you sir It clears alot.

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By default we've to assume 1 level paging?

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Yes, if nothing is talking about the number of paging level than, we can take 1 level paging.