Normally, tracing of all MPI events results in a large size of the trace file, even for relatively small applications. To reduce the trace file size, but be able to get an impression of the application bottlenecks, you can trace only the MPI functions that cause application load imbalance. That is, an MPI function is traced only if it was idle at some point of the application run, causing the imbalance. This functionality is implemented in the libVTim library.
You can enable source code locations tracing to identify the regions in source code that caused the imbalance (see Recording Source Location Information).
To generate an imbalance trace file, link your application with the libVTim library, using the -trace-imbalance option of mpirun, or one of the methods described here. For example:
$ mpirun -n 2 -trace-imbalance ./myApp
Open the generated .stf file to view the results. Intel® Trace Analyzer displays only the regions of MPI idle time. As a consequence, time values for MPI functions are equal to their idle time.