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Scalasca
========
Introduction
-------------------------
[Scalasca](http://www.scalasca.org/) is a software tool
that supports the performance optimization of parallel programs by
measuring and analyzing their runtime behavior. The analysis identifies
potential performance bottlenecks – in particular those concerning
communication and synchronization – and offers guidance in exploring
their causes.
Scalasca supports profiling of MPI, OpenMP and hybrid MPI+OpenMP
applications.
Installed versions
------------------
There are currently two versions of Scalasca 2.0
[modules](../../environment-and-modules.html) installed
on Anselm:
- class="s1">
scalasca2/2.0-gcc-openmpi, for usage with
[GNU Compiler](../compilers.html) and
[OpenMPI](../mpi-1/Running_OpenMPI.html),
- class="s1">
scalasca2/2.0-icc-impi, for usage with
[Intel Compiler](../compilers.html) and [Intel
MPI](../mpi-1/running-mpich2.html).
Usage
-----
Profiling a parallel application with Scalasca consists of three steps:
1. Instrumentation, compiling the application such way, that the
profiling data can be generated.
2. Runtime measurement, running the application with the Scalasca
profiler to collect performance data.
3. Analysis of reports
### Instrumentation
Instrumentation via " scalasca
-instrument" is discouraged. Use [Score-P
instrumentation](score-p.html).
### Runtime measurement
After the application is instrumented, runtime measurement can be
performed with the " scalasca -analyze"
command. The syntax is :
scalasca -analyze [scalasca options]
[launcher] [launcher options] [program] [program options]
An example :
$ scalasca -analyze mpirun -np 4 ./mympiprogram
Some notable Scalsca options are:
-t Enable trace data collection. By default, only summary data are
collected.
-e <directory> Specify a directory to save the collected data to.
By default, Scalasca saves the data to a directory with
prefix >scorep_, followed by name of the executable and launch
configuration.
Scalasca can generate a huge amount of data, especially if tracing is
enabled. Please consider saving the data to a [scratch
directory](../../storage.html).
### Analysis of reports
For the analysis, you must have [Score-P](score-p.html)
and [CUBE](cube.html) modules loaded. The analysis is
done in two steps, first, the data is preprocessed and then CUBE GUI
tool is launched.
To launch the analysis, run :
`
scalasca -examine [options] <experiment_directory>
`
If you do not wish to launch the GUI tool, use the "-s" option :
`
scalasca -examine -s <experiment_directory>
`
Alternatively you can open CUBE and load the data directly from here.
Keep in mind that in that case the preprocessing is not done and not all
metrics will be shown in the viewer.
Refer to [CUBE documentation](cube.html) on usage of the
GUI viewer.
References
----------
1. <http://www.scalasca.org/>