It is based on a post processing approach. Tracing Libraries - These trace all MPI calls.
Output is to the standard output.
As the MPI-2 standard makes it easy for users to define the routine to be called when an error is detected by MPI, the program can be made to automatically start a debugger when an error is detected, so that the problem can be diagnosed easily. In addition, one can also compile the MPE library with debugging code included. The MPI profiling interface provides a convenient way to add performance analysis tools to any MPI implementation. Thus MPE uses may also build and use these libraries with any MPI implementation. The first profiling library is that which accumulates the time spent in MPI routines and forms part of this tracing library.