Profiling GEOS-Chem with the TAU performance system

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  1. Parallelizing GEOS-Chem
  2. GEOS-Chem 7-day timing tests
  3. GEOS-Chem scalability
  4. GEOS-Chem 1-month benchmark timing results
  5. Profiling GEOS-Chem with the TAU performance system
  6. Speeding up GEOS-Chem

NOTE: This page is still under development. The Spack installation guide is still being validated.


The TAU Performance System is a profiling tool for performance analysis of parallel programs in Fortran, C, C++, Java, and Python. TAU uses a visualization tool, ParaProf, to create graphical displays of the performance analysis results.

Installing TAU

The best way to build TAU is with Spack. Please see these instructions at Github issue geoschem/geos-chem #637.

Compiling and running GEOS-Chem with TAU

To profile GEOS-Chem with TAU, you must first compile with the TAU_PROF=y Makefile option, e.g.:

 # Remove files from a previous compilation with TAU (if necessary)
 make tauclean

 # Compile with TAU profiling
 make TAU_PROF=y ...etc. other makefile options ...

It is important that you compile on a single processor (i.e. don't pass -j4 or -j8) to allow TAU to properly instrument the code.

The TAU_PROF=y option will set COMPILE_CMD instead of COMPILE_CMD :=$(FC) where FC is gfortran or ifort.

Once you have compiled GEOS-Chem with TAU_PROF=y, you can run GEOS-Chem as you normally would. GEOS-Chem will create profile.* files containing the profiling information.

Using ParaProf to create plots from the profiling data

In your run directory, there should be one or more profile.* files. The number of profile.* files will depend on the number of CPUs that you use for your GEOS-Chem simulation. To pack all of the profiling data into a single file, type:

paraprof --pack GEOS-Chem_Profile_Results.ppk

Then run paraprof on the packed format (.ppk) file using:

paraprof GEOS-Chem_Profile_Results.ppk

This will open two windows, the ParaProf Manager window and the Main Data window. For more information on how to interpret the profiling data, see the ParaProf User's Manual.

If you click on the the bar labeled "thread0" in the ParaProf manager window, you can generate a plot that looks like this:


The value displayed, the units, and the sort order can be changed from the Options menu. The time that each subroutine spent on the master thread is displayed as a histogram. By examining the histogram you can see which routines are taking the longest to execute. For example, the above plot shows that the COMPUTE_F routine (highlighted with the red box) is spending 444 seconds on the master thread, which is longer than the Rosenbrock solver takes to run. This is a computational bottleneck, which was ultimately caused by an unparallelized DO loop.

To save the plot, select "Save as Bitmap Image" from the File menu. In the Save Image File window, you may select the output type (JPEG File or PNG file) and specify the file name and location.

--Melissa Sulprizio (talk) 22:48, 8 February 2017 (UTC)
--Bob Yantosca (talk) 16:55, 10 February 2017 (UTC)

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