Adventures in Mastering the Use of Performance Evaluation Tools Manuel Ríos Morales ICOM 5995 December 4, 2002

Overview  Project Proposal Original Goals Problems Encountered  Project Changes Revised Goals New Problems  Final Revision

Project Proposal  Original Goals Master a performance evaluation tool and use it to evaluate the performance of an existing benchmark. Tool selected: AIMS Benchmark: FT kernel of the NPB  Why AIMS? Provides tools for measurement and analysis of performance of parallel programs. Can be used to highlight problem areas that can be modified to improve program execution.

Problems Encountered  Installation Quite challenging Required modification of makefiles and debugging of some modules  Instrumentation Couldn’t be achieved due to bugs in the software.

Problems Encountered (cont.)

Project Changes  Revised Goals Performance evaluation tool changed to Vampir.  New Problems Compilation of the FT benchmark Installation of VampirTrace

Final Revision  Project goals Understanding basic features of Vampir with the use of an example provided in the Vampir package.

Vampir Analysis Tool  Vampir consists of two packages: Vampir: Tracefile visualization program with a graphical user interface for XWindows desktops. VampirTrace: Instrumented MPI library to link with the user code for automatic tracefile generation on a parallel platform.

VampirTrace  Tool for MPI applications that produces tracefiles that can be analyzed with Vampir.  Records all calls to the MPI library and all transmitted messages.  Allows defining and recording arbitrary user defined events.  Using it requires relinking the application with the VampirTrace profiling library.

VampirTrace (cont.)  mpicc -o test test.c -L/$HOME/VampirTrace/lib/libVT.a –lVT  patch_mpicc Modifies mpicc command to include the –vt option  Mpicc –vt –o test test.c

Vampir  Tool for visualization and analysis of MPI programs  Understand the application behavior  Analyze the performance of subroutines or code blocks  Learn about communication patterns, parameters and performance  Identify communication hotspots

Vampir (cont.)  Basics Loading Tracefiles Displays

Global Timeline Display

Global Timeline Display (cont.)  It will automatically open when paused or finished loading a tracefile.  Shows all analyzed state changes for each process over the complete period of time in one display.  Zoom ability allows getting detailed information of the runtime behavior of the traced program.

Activity Chart Display  Shows a statistic about the time spent in each activity individually for each process defined in the tracefile.

Summary Chart Display  Displays the sum of the time consumed by all instrumented activities over all selected processes.

Final Thoughts  Tools that facilitate the instrumentation and visualization of parallel program execution are invaluable.  Programmers can benefit from using these tools since the help highlight any problem areas that can be modified to improve program execution.