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Consider the system which has virtual address of 36 bits and physical address of 30 bits and page size of 8
KB, page table entry contain 1 valid bit, 2 protection bit and 1 reference bit. Then the approximate page
table size in (MB) is ________.
in CO and Architecture by Active (2.3k points) | 115 views
hmm i am also going to add that but didnt

21 is real answer but they say 24  ....they take appox. thing too seriously
if gate ask this type of question then i think 21 is correct than 24
They will specify everything properly..


A page entry should be padded if its not in byte, for 21 bits we should add 3 bits more to make it 3B entry, isn't this is a default thing why they need to specify?


@Swapnil Naik

we cannot pad by default , actually here said approximate pte size so they padded

Okay got it.

I think Page Table Entry should be padded. A similar question was asked in Gate which is as below.

(Without padding the answer would have been 1.75 MB and using padding the answer is 2 MB) 

Also in many practical implementations, the Page table entry is rounded up as it is said in the below link.


Agreed, Memories are word addressable. If the entries are not padded, accessing them will be difficult as the starting point of entry will be in between somewhere in a byte and not at the beginning at byte.

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