Parallel Operating Environment Lab Exercises

Cornell Theory Center

Lab Exercise
Parallel Operating Environment (POE)

Runs on: SP interactive nodes

Prerequisites

This lab follows the talk IBM SP Parallel Environment (PE).

Overview

This exercise asks you to run a program under POE several times, modifying the setting of one POE environment variable for each run. The sample program provided is a very simple "hello, world" program. POE can run multiple instances of this serial program in parallel on several nodes.

If you get stuck, click on the "Solution" button at the end of each question.

This exercise will probably take no more than 30 minutes to complete.

Before You Begin

If you are using the VWC, choose Login, then Access Lab Files, then skip ahead to the next section, "Exercise: . . ".
If you are using a telnet window, open that window and log on to the SP now.
Create an empty subdirectory to work in so that the files from this tutorial do not get mixed up with your other files. Use the UNIX cp command to copy the tutorial files to your subdirectory. The files that you need to run this tutorial are in this directory: /usr/local/doc/www/Edu/Tutor/POE
Type these commands:
(notice the period at the end of the cp command, which refers to your current directory).
You can also copy tutorial files from within your web browser, but this will store the files on your local machine or workstation (wherever your web browser is running), not on the SP. Some browsers add or replace characters when files are copied.

Exercise: Compile and run a program under POE

First, look at either hello.c or hello.f and compile it. Although the sample program does not contain any message passing calls, it won't hurt to use one of POE's compiler scripts for practice. [ Solution ]
Try to run the sample program without setting any environment variables. What error message do you see? [ Solution ]
Correct the error reported in the previous step, and try running again. Hint: If you want more than one node, you will need to set more than one environment variable. [ Solution ]
Explicitly choose the Internet Protocol (ip) communications subsystem library and the high-performance switch (css0) adapter. [ Solution ]
To see which node sent which message, set the environment variable MP_LABELIO and run again. Notice that the messages may appear in any order; task 0 is not necessarily first. [ Solution ]
Ask for a list of nodes on which your program is running. [ Solution ]
Get lots of information about exactly what POE is doing by setting the environment variable MP_INFOLEVEL to 2. [ Solution ]

Cleanup

If you wish to delete the directory and files you created for this exercise:

If you are using the VWC, choose Delete below the "Edit or View Lab Files" window. When that step is complete, choose Logout to end your connection to the SP.
If you are using a telnet window, change directories up one level and delete the lab directory you created earlier, and its contents.

URL http://www.tc.cornell.edu/Edu/Tutor/POE/