0 votes 0 votes A TLB is a hardware device used for speeding up the conversation from virtual address to physical address. Consider a memory management unit where a memory reference takes 500 nanoseconds; TLB (Translation Look aside Buffer) reference takes 40 nanoseconds; and the hit-rate achieved with the use of TLB is 80%. The speed-up (in %) we gained using TLB technique compared to the pure paging with no TLB ____ Here I got EMAT using TLB ==> 640ns EMAT wthout TLB ==> 1000ns how to calculate speed Up.? Operating System made-easy-test-series operating-system translation-lookaside-buffer + – jatin khachane 1 asked Dec 13, 2018 • edited Mar 4, 2019 by akash.dinkar12 jatin khachane 1 886 views answer comment Share Follow See all 7 Comments See all 7 7 Comments reply goxul commented Dec 13, 2018 reply Follow Share Look at it this way: if the price of X was 100 and it went to 150, we say there was a 50 % increase. If it came to 50, we say there was a 50 % decrease, as compared to the original price. Similarly, if the original time was 1000 ns and it came to 640 ns, the speedup was (1000-640) = 360 ns, which is 36 % of 1000. We care about the change in value as compared to the original value. 0 votes 0 votes neeraj33negi commented Dec 13, 2018 reply Follow Share Speedup = $\frac{(old value - newvalue)}{oldvalue} * 100$ 0 votes 0 votes Hemanth_13 commented Dec 13, 2018 reply Follow Share Is it 1.56 ? 0 votes 0 votes jatin khachane 1 commented Dec 13, 2018 reply Follow Share But in COA pipelining we calculated SU = [ T(without pipeline) / T(with pipeline) ] We didnt consider difference there .. 0 votes 0 votes neeraj33negi commented Dec 13, 2018 reply Follow Share yes, in COA we are asked speedup which means how new value performs relative to old value but since here percentage is asked you have to consider difference. What if cost of an item was 1000 and now it is 500 the speedup is simply : 500/1000 = 1/2 that means item is now half of the original value OR (1000-500)*100/1000 i.e. 50% cheaper. If you did (1000/500)*100 i.e 200%, it would mean item is now 200% cheaper which makes no sense. 0 votes 0 votes jatin khachane 1 commented Dec 13, 2018 reply Follow Share Only speedup is asked then [ Told / Tnew ] If speedup % asked then [ (Told - Tnew) / Told ] * 100 -------------------------------------------------------------------------------- I cOA aslo if percentage speedup asked we should take differnce ??? @Shaik Masthan Can you please check this 0 votes 0 votes dmchaudhary commented Dec 14, 2018 reply Follow Share Answer is 36%.correct me if i am wrong. 1 votes 1 votes Please log in or register to add a comment.
0 votes 0 votes Speed up will always be calculated as (time for slow processing / time for fast processing) here, 1000ns without tlb is slower, 640ns with tlb is faster so, speedup=1000/640=>1.5625 Speedup gain=(1.5625-1)*100=>56.25% Sarang answered Jan 16, 2022 • edited Jan 16, 2022 by Sarang Sarang comment Share Follow See 1 comment See all 1 1 comment reply Kabir5454 commented Jan 16, 2022 reply Follow Share Question is asking about how much speed up we gained i guess..!! which is (1000-640)/1000 *100 % 0 votes 0 votes Please log in or register to add a comment.