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VTune
Intel® VTune™ Profiler is an accurate performance analysis tool with low overhead for serial and multithreaded applications. Use VTune Profiler:
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Using Intel VTune
To perform the performance analyse of your application with VTune you don’t need special compiler wrapper or libraries. Just recompile and relink your code with extra –g option in order to include debug information. VTune works well for dynamically linked binaries. Here you can find some tips for statically linked binaries.
Example. Modules on Hawk:
module load vtune # set up VTune environment module load gcc mpt
Example. Modules on Vulcan:
module load performance/vtune/2020.1 # set up VTune environment module load mpi/openmpi/4.1.1-gnu-11.1.0
Compilation example:
mpicxx –O2 -g -Wl,-Bdynamic main.cpp
Run analysis
VTune has both a GUI and command line tool: vtune-gui and vtune. The following types of analysis are available on Hawk:
- hotspots - Analyze application flow and identify sections of code that take a long time to execute (hotspots).
- threading - Discover how well your application is using parallelism to take advantage of all available CPUs. Identify and locate synchronization issues causing overhead or idle wait time resulting in lost performance.
- memory-consumption - Analyze memory consumption by your Linux application, its distinct memory objects and their allocation stacks.
IMPORTANT The VTune project working directory and the results directory must be placed on lustre FS.
Example for your job script:
..
module load vtune
module load gcc mpt
WORKDIR=/your/project/dir/on/lustre
cd ${WORKDIR}
mpirun -np 128 vtune -collect hotspots -r ${WORKDIR}/results_dir -- ./a.out your_input.file
Report
When VЕune completes the analysis, you can open the results in the vtune-gui tool. Alternatively you can also generate the report in text form using the VTune command line tool:
vtune -help report
vtune -report summary -r ${WORKDIR}/results_dir
For some use cases you might need to limit the amount of raw data to be collected. Define this limit in MB through the data-limit option:
mpirun -np 128 vtune -collect hotspots -data-limit=200 -- ./a.out
Some more information about VTune you can find here.