4 votes 4 votes Free disk space can be kept track of using a free list or a bitmap. Disk addresses require $\text{D bits}$. For a disk with $\text{B blocks}$ and $\text{D}$ having the value $\text{32 bits},$ the percentage of the disk space that must be free for free list to use same memory as bitmap will be _________ (up to three decimal place). Operating System go2025-mockgate-3 numerical-answers operating-system file-system file-organization + – gatecse asked Jan 26, 2021 • recategorized Jan 26, 2021 by soujanyareddy13 gatecse 684 views answer comment Share Follow See all 2 Comments See all 2 2 Comments reply mrinmoyh commented Feb 3, 2021 reply Follow Share For Bitmap we’re using 1 bit for a block & for Free list we’re using 32 bits for a block 2 votes 2 votes Venky8 commented Jan 13, 2022 reply Follow Share Similar question: https://gateoverflow.in/1740/Gate-cse-1998-question-25-a 0 votes 0 votes Please log in or register to add a comment.
Best answer 5 votes 5 votes Let block size be $k$ and $F$ be the number of free blocks. Free list size $=F*D*k$ bits Bitmap size $=B*k$ bits So, we require $F*D*k = B*k \implies F *D=B.$ When $D=32$ bits, $\implies F/B = 1/32 = 3.125\%.$ gatecse answered Jan 26, 2021 • selected Jan 1, 2022 by Arjun gatecse comment Share Follow See all 2 Comments See all 2 2 Comments reply akashrawat commented Jan 19 reply Follow Share We shouldn’t have multiplied by $k$ ie. block size as the unit of space(memory) becomes $bits\ bytes$ instead of $bit$. 0 votes 0 votes Quantum City commented Jan 19 reply Follow Share @GO Classes @Deepak Poonia @GO Classes sir this should not be the correct answer i guess or question is ambiguous as question is asking the percentage of the disk space that must be free for free list to use same memory as bitmap. Meaning size of free list should be same as bitmap thus, size of free list is B bits. thus, answer should be $(B/8)/(B*size of block)=1/(8*size of block)$. Correct me if I’m wrong 1 votes 1 votes Please log in or register to add a comment.
13 votes 13 votes Hope this helps . Ans is 3.125 Subhajit Panday answered Jan 27, 2022 Subhajit Panday comment Share Follow See all 0 reply Please log in or register to add a comment.