1. [30 points] A computer is designed to use a 4-stage pipeline, and each stage
ID: 3871636 • Letter: 1
Question
1. [30 points] A computer is designed to use a 4-stage pipeline, and each stage needs 2 nsec to complete its job. 1) [10 points] How much time does it take for the computer to complete the execution of one instruction? 2) [10 points] What MIPS can this computer reach? 3) [10 points] If the designer decides to merge 3 and 4 into a stage, and this nevw stage takes 4 nsecs to work on each instruction. Therefore this new computer pipeline now has three stages, and the time each stage needs to complete its job is 2ns, 2ns, and 4ns. the a. [3 points] How many instructions can be concurrently executed by this computer? b. [7 points] What MIPS can now this computer reach?Explanation / Answer
Hi,
Execution time of pipeline = (k+n-1)* t
where k is no of stages, n- number of instructions, t- max of all stages execution time
1. a. here all stages same execution time 2nsec
execution time for n=1 is
= 4*2= 8nsec
hence for 1 million instructions it takes- 10^6 *8 * 10^-9 = 8 milli sec
therefore in 1 sec it can execute 1/8*10^-3 = 125MIPS
c.given now stages reduced to 3, hence
b. time for single instruction = 3* 4(max of 2,2,4) = 12 n sec
hence for 1 million instructions it takes- 10^6 *12 * 10^-9 = 12 milli sec
therefore in 1 sec it can execute 1/12*10^-3 = 83.33 MIPS
Thumbs up if this was helpful, otherwise let me know in comments
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