Question

Computer Architecture

6. We can choose pipelined or non-pipelined implementation like below. For a program with 20% ALU instructions, 10% control instructions and 70% memory instructions, which design will be faster? Give a quantitative CPI average for each case. (you have to write all process like CPI, CPI time, etc) Non-Pipelined version Parameter Clock Rate CPI for ALU instruction CPI for Control instruction 2 CPI for Memory instruction3 Pipelined version 250 MHz 600 MHz

Answer 1

PipeLined version
ALU instruction 20% 1
Control instructions 10% 2
Memory instructions 70% 3
clock Rate = 250 MHz

average CPI = 0.2*1 +0.1*2 + 0.7*3
   => 0.2 + 0.2 + 2.1 =>2.5
average time of execution = 2.5/(250*10^6) = 10 nanosecond

Non-PipeLined version
ALU instruction 20% 1
Control instructions 10% 1
Memory instructions 70% 1
clock Rate = 600 MHz

average CPI = 0.2*1 +0.1*1 + 0.7*1
   => 0.2 + 0.1 + 0.7 =>1
average time of execution = 1/(600*10^6) = 1.67 nanosecond

Here Non-PipeLined version takes lesser time then PipeLined version
Therefore ,Non-PipeLined version is faster