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edited | 130 views
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shouldn't doubling the associativity increase the tag bit by 1?
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@Markzuck

Coming to the question, no.of tags = no.of lines in the cache.

Associativity effects the number of tag bits but not number of tags

S1 always true, s2 always false, s3 always true

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Sorry for the screenshot.

But ans given is b?

How can number of tags change without change in no of tag bits?
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But ans given is b?

Do you think answers provided by them are always correct ?

How can number of tags change without change in no of tag bits?

Doesn't get what you are saying, read one more time my previous comment

Sorry for the screenshot

atleast edit it now.

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S1 always true, s2 always false, s3 always true

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today one more student post the same questions and I write the answer in  very well manner
at the time I save my answer he is just lock the question and my answer was remove :3

I tell him to unlock it so that I can auto-load my content but he didn't do that -_-
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@Magma

either mine or made easy ? note that madeeasy provide s2 and s3 are true but i am saying s1 and s3 are true.

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@Magma

can you explain ? before that just read my comment

+2

S1 :

Direct mapping :

 TAG LINE NUM BO

dOUBLING the line size ---- > Block offset is decrease by /2

In direct mapping we know that  no of lines * block offset  = cache size

therefore , even if you increase the line size , the block offset will decrease by same , SO overall cache size remains const

therefore , TAG bits is const

SET - ASSOCIATIVE MAPPING  :

 TAG SET NUM BO

DOUBLING the line size -----> NUMBER OF SETS  INCREASE BY X 2  ----> NUMBER OF BLOCKS ARE DEDUCE BY 2 ----> BO IS DECREASE BY /2

so ,if we increase 1 bit from line number ----> it will decrease 1 bit from the BO

therefore , In any cache organization you observe that (sets * block size = const) as long as you put this "k" as const where k is k-way set associativity

therefore , no of tags remain const in set-associtive mapping

 tag block off

doubling line size ---- > number of blocks deduce ----> block offset also deduce

therefore TAG bit is increase here

therefore we conclude that by doubling the line size implies higher tag bits

S1 is false always

s2 : Doubling the associativity doubles the number of tags in the cache

 TAG SET NUM BO

doubling the associativity means

set number decreases and here block size is fixed  (given )

therefore it doubles the number of tags in the cache

S2 is right always

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we have to fix the cache size, right ?
+1
yess
+1

@Magma

it is asking about no.of tags but not number of tag bits, i already mentioned in my comment

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I did bad mistakes always :3