CS475 Lab 7 Iso-efficiency

In this lab you will determine the iso-efficiency of summing n numbers on a one dimensional grid of processors P1-P2-P3-...-Pp. This is a 1-D version of the exercise done in Lecture QuinnChapter7, slides 26 and on.

It takes 1 time step to add two numbers, and 500 time steps to communicate a message from Pi to Pi+1 , or Pi+1 to Pi, no matter how large the message.

Lab Report

• Determine T1 and Tp, in terms of n and p
• Determine Sp, in terms of n and p
• Determine Ep, in terms of n and p
• Make a table for Ep for rows n = 6000, n=36000, n=168000
  and columns p=2, p=4, p=8
• What is the efficiency on the diagonal of the table?
• Express the iso-efficiency of adding n numbers on a 1D grd of processors in terms of p.