Optimization Topics Exercise


  1. Login to the SP machine

    Make sure that you are logged into your assigned SP node with your assigned userid for this exercise. Ask the instructor if you have any questions.

  2. Verify the environment variable $WORKSHOP

    The $WORKSHOP variable defines the root location for the workshop files, and may vary from workshop to workshop. Find out if this has already been setup for your workshop:

    echo $WORKSHOP

    If this environment variable is not set, check with the instructor for the correct location. Then, depending upon your shell, set $WORKSHOP:

    csh/tcsh 
    setenv WORKSHOP instructor/specified/path
    bsh/ksh 
    export WORKSHOP=instructor/specified/path

  3. Copy the example files

    In your SP home directory, create a subdirectory for the Optimization Topics test codes and cd to it.

    mkdir ~/optimization
    cd ~/optimization

    Then, copy the exercise files to your optimization subdirectory:

    C: 
    cp  $WORKSHOP/optimization/samples/C/*   ~/optimization
    Fortran: 
    cp  $WORKSHOP/optimization/samples/Fortran/*   ~/optimization

  4. List the contents of your optimization subdirectory

    You should notice a number of files, depending on whether you copied the C, Fortran or both versions. The complete set is shown in the table below.

    C Files Fortran Files Description
    arit01.c arit01.f Strength reduction: Horner's rule
      arit02.f Right shift replacement for integer division by a power of 2
      arit03.f Factorization
      arit04.f Common Subexpression Elimination
      arit05.f Real*16 vs. Real*8
    arraypad.c arraypad.f Array padding
      iotest.f I/O
    loop01.c loop01.f Loop fusion
    loop02.c loop02.f Loop fusion
    loop03.c loop03.f Loop interchange
    loop05.c loop05.f Invarient IF code floating
    loop06.c   Invarient IF code floating
    loop08.c loop08.f Loop Defactorizing
    loop10.c loop10.f Loop collapse
    loop11.c loop11.f Loop unrolling
    loop12.c   Loop unrolling and sum reductions
    loop13.c loop13.f Outer loop unrolling
    mem01.c mem01.f Stride effects
    opt01.c   Small errors: non-associative floating point operations
    opt02.c   Large errors: Catastrophic cancellation

  5. Review, compile and run the example codes

    Select any/all of the sample codes. After reviewing the optimization technique being used, compile each of your selected codes. Use the xlf and xlc compiler as appropriate, for your compilations.

    Run your executables and compare your results against those shown in the Optimization Tutorial.

    If you have an application or program of your own, and time permits, try employing any of the optimization techniques with it. The instructor is available for assistance should you decide to do this.

This concludes the Optimization Topics lab exercise.