hw1_assignment

Hw1_assignment - HW1 Assignment Problem 1 Solve P1.7 P1.8 P1.9 and P1.10 in Chapter 1 of the Shen/Lipasti textbook 1 TABLE 1 Given the parameters

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HW1 Assignment Problem 1: Solve P1.7, P1.8, P1.9, and P1.10 in Chapter 1 of the Shen/Lipasti textbook. 1. Given the parameters of Problem 6, consider a strength-reducing optimization that converts multiplies by a compile-time constant into a sequence of shifts and adds. For this instruction mix, 50% of the multiplies can be converted to shift-add sequences with an average length of three instructions. Assuming a fixed frequency, compute the change in instructions per pro- gram, cycles per instruction, and overall program speedup. 2. Recent processors like the Pentium 4 processors do not implement single-cycle shifts. Given the scenario of Problem 7, assume that s = 50% of the additional integer and shift instruc- tions introduced by strength reduction are shifts, and shifts now take four cycles to execute. Recompute the cycles per instruction and overall program speedup. Is strength reduction still a good optimization? 3. Given the assumptions of Problem 8, solve for the break-even ratio s (percentage of addi- tional instructions that are shifts). That is, find the value of s (if any) for which program per- formance is identical to the baseline case without strength reduction (Problem 6). 4. Given the assumptions of Problem 8, assume you are designing the shift unit on the Pentium 4 processor. You have concluded there are two possible implementation options for the shift unit: 4-cycle shift latency at a frequency of 2 GHz, or 2-cycle shift latency at 1.9 GHz. TABLE 1 CPI computation Type Old Mix New Mix Cost CPI store 15% 1 load 25% 2 branch 15% 4 40% 1 multiply 5% 10 Total 100% TABLE 2 CPI computation Type Old Mix New Mix Cost CPI store 15% 1 load 25% 2 branch 15% 4 integer 35% 1 shift 5% 4 multiply 5% 10 Total 100%
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Assume the rest of the pipeline could run at 2 GHz, and hence the 2-cycle shifter would set the entire processor’s frequency to 1.9 GHz. Which option will provide better overall perfor- mance? Problem 2: Solve P2.4, P2.5, P2.6 in Chapter 2 of the Shen/Lipasti textbook.
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This note was uploaded on 03/02/2012 for the course ECE 752 taught by Professor Profgurisohi during the Spring '09 term at Wisconsin.

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Hw1_assignment - HW1 Assignment Problem 1 Solve P1.7 P1.8 P1.9 and P1.10 in Chapter 1 of the Shen/Lipasti textbook 1 TABLE 1 Given the parameters

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