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craypat

Description

Description

CrayPAT is a performance analysis tool for evaluating program execution on Cray systems. CrayPat consists of three major components:

  • pat_build – used to instrument the program to be analyzed
  • pat_report – a standalone text report generator that can be used to further explore the data generated by instrumented program execution
  • Apprentice2 – a graphical analysis tool that can be used, in addition to pat_report, to further explore and visualize the data generated by instrumented program execution

These components are described in greater detail in the pat_build, pat_report, and app2 man pages, respectively. You must have the perftools module loaded first to get these man pages. In addition, more detail about CrayPat usage and environment variables is provided in the intro_craypat man page.

Usage

Usage

Follow these 10 STEPS to perform the basic analysis of your program using CrayPat and Apprentice2 tools. Since CrayPat is a performance analysis tool, not a debugging tool, start with a fully debugged and executable program. The program must be capable of running to a planned completion or an intentional termination before CrayPat can be used. Load the programming environment modules first. This ensures that the correct links and libraries are in place with your choice of compiler and target execution environment. For example, if you are working on a Cray XT series system using CNL on the compute nodes, enter the following command:

Step 1: Load CrayPat & Cray Apprentice2 module files

module load perftools

Then build your application. With the CrayPat module loaded remake your program using the compiler option to preserve all .o files (and .a files, if any) created during compilation. CrayPat requires access to the object files (and archive files, if any). For example, if you are working with a Fortran program, enter commands similar to the following:

Step 2: Build application

ftn -c my_program.f
ftn -o my_program my_program.o

Or simply use your makefile

make clean
make

Using Automatic Program Analysis(APA). To use automatic program analysis, follow these steps. Use the pat_build command to insert APA code into your program. The instrumented copy is saved under a new name with the extension +pat. Note that the original program remains unchanged.

Note: When building in your /tmp/work or /tmp/proj area, a copy of the build’s .o files will, by default, be placed in /ccs/home/$USER/.craypat. This may increase your home directory usage above quota. The PAT_LD_OBJECT_TMPDIR environment variable can be used to control the location of the .craypat directory. For example, setenv PAT_LD_OBJECT_TMPDIR /tmp/work/$USER .

Step 3: Instrument the original program

pat_build -O apa my_program

This produces the instrumented executable my_program+pat.

Execute the program. During execution, the specified performance analysis data is collected and written to one or more data files, depending on the experiment being conducted. On a Cray XT series CNL system, programs are executed using the aprun command.

Step 4: Run the instrumented executable

aprun -n <numproc> my_program+pat

Or simply submit a PBS script

qsub test.pbs

This produces the data file my_program+pat+PID-nodesdt.xf, which contains basic asynchronously derived program profiling data. After program execution completes or terminates, use the pat_report command to create a .apa report.

Step 5: Use pat_report to process the data file

pat_report -T -o report1.txt my_program+pat+PID-nodesdt.xf

This produces three results:

  • a sampling-based text report to report1.txt
  • an .ap2 file (my_program+pat+PID-nodesdt.ap2), which contains both the report data and the associated mapping from addresses to functions and source line numbers
  • an .apa file (my_program+pat+PID-nodesdt.apa), which contains the pat_build arguments recommended for further performance analysis

Once a .apa file is created, you can open the file in your preferred text editor and verify that you do not wish to have more or less profiled. Lines that are preceded with # will be ignored. Any option to pat_build may be added to this file. For most users, the file created by pat_report will be sufficient.

Step 6: Reinstrument the program

Reinstrument the program, this time using the .apa file.

Most common values are:

  • -g mpi
  • -g blacs
  • -g blas
  • -g io
  • -g lapack
  • -g lustre
  • -g math
  • -g scalapack
  • -g stdio
  • -g sysio
  • -g system

After you have verified this file, rebuild your executable as follows.

Step 7: Rebuild the program

pat_build -O my_program+pat+PID-nodesdt.apa

It is not necessary to specify the program name, as this is specified in the .apa file. Invoking this command produces the new executable, my_program+apa, this time instrumented for enhanced tracing analysis.

Step 8: Run the new instrumented executable

aprun -n <numproc> my_program+apa

Or simply submit a PBS script

qsub test.pbs

This produces the new data file my_program+apa+PID2-nodesdt.xf, which contains expanded information tracing the most significant functions in the program.

You can use this file as input to pat_report, for text reports, or apprentice2, for graphical analysis. By default, your code will gather hardware counters from hwcp group 0. This can be overridden at runtime by setting the PAT_RT_PERFCTR environment variable (see man hwpc). To ignore hwpc data in your text reports, use the -H option to pat_report.

Step 9: Use pat_report to process the new data file

pat_report -T -o report2.txt my_program+apa+PID2-nodesdt.xf

This produces two results:

  • a tracing report to report2.txt
  • an .ap2 file (my_program+apa+PID2-nodesdt.ap2), which contains both the report data and the associated mapping from addresses to functions and source line numbers

Step 10: View results in text and/or with Apprentice2

app2 my_program+apa+PID2-nodesdt.ap2

Versions

Available Versions

System Application/Version
Titan perftools/6.1.4
Titan perftools/6.2.0
Titan perftools/6.2.3
Titan perftools/6.2.4
Titan perftools/6.2.5
Titan perftools/6.3.0
Titan perftools/6.3.1
Eos perftools/6.1.1
Eos perftools/6.1.4
Eos perftools/6.2.0
Eos perftools/6.2.4
Eos perftools/6.2.5
Eos perftools/6.3.0
Eos perftools/6.3.1