506 fall 2014 MIPS01-------------------------------------------------------------------------------1.Entil Corporation currently produces three various processors, all executing the same set of machine instructions: - P1 has a 2.7 GHz clock rate and an advertised CPI the 1.2 - P2 has a 3.4 GHz clock rate and also an advertised CPI the 1.6 - P3 has actually a 3.8 GHz clock rate and an advertised CPI that 1.8 a) <15 points> making use of IPS (instructions every second) together your criterion, and also accepting the information offered above, which processor provides the finest performance? Justify her conclusion precisely. Answer: A tiny dimensional analysis yields the truth that: IPS = ClockRate / CPI = (cycles/second) / (cycles/instruction) So: IPS_1 = 2.7 x 10^9 / 1.2 = 2.250 x 10^9 IPS_2 = 3.4 x 10^9 / 1.6 = 2.125 x 10^9 IPS_3 = 3.8 x 10^9 / 1.8 = 2.111 x 10^9 (approximately) Therefore, by this measure, P1 supplies the finest performance. B) <10 points> that takes 24 secs (of CPU time) to execute a specific benchmark ~ above P1. Just how many an equipment instructions room executed once that benchmark is run on P1? Justify your conclusion precisely. Answer: indigenous the ahead part, on P1 we execute (on average) 2.25 x 10^9 instructions per second. So, in 24 seconds the variety of instructions executed would be 24 x 2.25 x 10^9 = 54 x 10^9 c) <15 points> Entil would choose to mitigate the execution time of the benchmark on P1 by 25%, yet the redesign they"ve come up v would entail increasing the CPI by 20%. What clock rate must they use in stimulate to attain their goal? Justify her conclusion precisely. Answer: The brand-new CPI would certainly be 1.2 x 1.2 (120% of the old CPI) or 1.44 cycles every instruction. No a readjust in CPI nor a readjust in the clock price will readjust the variety of instructions required to execute the benchmark, therefore that"s quiet 54 x 10^9. Now we recognize that ExecTime = # accuse x CPI x seconds/cycle since seconds/cycle = 1/ClockRate, a little algebra yields the truth ClockRate = # instructions x CPI / ExecTime So, to achieve the preferred result, the execution time must be 18 seconds, and also so ClockRate = 54 x 10^9 x 1.44 / 18 = 4.32 x 10^9 cycles/second i m sorry is a clock rate of 4.32 GHz. D) <15 points> girlfriend were given "advertised" CPI worths for every of the three processors. Briefly comment on how Entil can have determined those CPI values. Keep in mind the it is common for different varieties of device instructions come require various numbers the clock cycles. Answers: there are several scenarios we could consider; I will analyze one. I think Entil wants to produce an "honest estimate" the will give potential users information that is likely to conform to their actual suffer if they do embrace this processor. Using the results from running any type of single, really application with one collection of entry data is not most likely to attain that goal, due to the fact that different applications will more than likely use various mixes that instructions, and also because the selection input data can greatly change the power of a program. One strategy would be to choose a suite of programs Entil would suppose a typical user to it is in interested in, and time those programs v a variety of intake data sets. (Of course, this would also require somehow measuring the actual number of instructions the were enforcement in each of those tests, i m sorry is an overwhelming but possible.) native those results, some type of weight average might be computed, perhaps taking into account some see of the relative importance of the assorted programs the were selected.2. Every of 2 processors support 4 classes the instructions, and each class of instruction has the CPI shown below on each of the processors: Instruction class P1 P2 arithmetic/logical 1 2 load/store 10 8 conditional branch 2 1 unconditional branch 1 2 a) <15 points> making use of default options, gcc compiles a specific program so that the executable has 40% arithmetic/logical instructions, 25% load/store instructions, 25% conditional branch instructions, and also 10% unconditional branch instructions. (In various other words, these percentages reflect the executable indigenous a static allude of view). I think that when the regimen is executed, those exact same percentages that instructions will certainly be executed. What would be the average CPI if this executable is run on every of the 2 processors explained above? Justify your conclusions precisely. Answer: AvgCPI for P1 = .40 * 1 + .25 * 10 + .25 * 2 + .10 * 1 = .40 + 2.5 + .50 + .10 = 3.5 AvgCPI because that P2 = .40 * 2 + .25 * 8 + .25 * 1 + .10 * 2 = .80 + 2.0 + .25 + .20 = 3.25 b) <15 points> What execute your answers to component a) tell you around the loved one performance that P1 and P2, once executing this specific program? Explain. Answer: for sure nothing. Us don"t know the clock prices of the 2 systems, and also without that we cannot to express the to run time for the regime on either system. The course, if we were to do an unwarranted assumption (say, the the clock prices are the very same for both systems), we can then reach an unwarranted assumption. C) <15 points> You to be told in component a) to i think (among other things) that if 40% the the maker instructions in the compiled routine were arithmetic/logical, then once the regimen was run 40% that the an equipment instructions that would certainly be executed would certainly be arithmetic/logical. Briefly comment on whether the is a reasonable assumption. The is acceptable to think about the inquiry from the view of C code fairly than maker code. It is recipient to include an example or 2 in your discussion.
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Answer: the is no reasonable. Us would mean that few of the an equipment instructions room in loops or choice mechanisms, and so that several of the individual machine instructions would be executed plenty of times and others can not be executed at all