GATE CSE 2008 | Question: 38

Question

In an instruction execution pipeline, the earliest that the data TLB (Translation Lookaside Buffer) can be accessed is:

• A. before effective address calculation has started

• B. during effective address calculation

• C. after effective address calculation has completed

• D. after data cache lookup has completed

Comments

Nitesh Singh 2

TLB stores only page table of large size program(Programs which are unable to fit in main memory)

i think you mean “virtual memory” here instead of TLB. 

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Should this be tagged as operating system? #operating-system?

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The data TLB translates virtual to physical addresses, so it needs the complete virtual address first. This address is only available after effective address calculation finishes. Hence, TLB access starts after that point.

Answer 1

Answer - (C)

The effective address is like a house number, but for computer memory. The TLB is like a phone book that tells you which physical address (the actual location of the house) corresponds to each effective address.

Before you can access data in the TLB, you need to know the effective address. This is like finding the house number in the phone book. Once you have the effective address, you can look up the corresponding physical address in the TLB.

If the effective address is not in the TLB, you need to look it up in the page table, which is like calling the post office to get the address. This can take a while, so it's best to try to keep the TLB up to date.

Answer 2

B. during effective address calculation

Comments

@ Sandeep

an effective address is Virtual address and after Virtual address calculation we look into TLB. So option C is correct.

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@Bikram sir sir

it means after calculation of effective/logical address we look into TLB to check whether  data is present or not

this is the reason for C option

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@set2018

Yes correct