A light-weight MPI profiler.

mpiP is a light-weight profiling library for MPI applications. Because it only collects statistical information about MPI functions, mpiP generates considerably less overhead and much less data than tracing tools. All the information captured by mpiP is task-local. It only uses communication during report generation, typically at the end of the experiment, to merge results from all of the tasks into one output file.

The current version of mpiP can be accessed at https://github.com/LLNL/mpiP/releases/latest.

Version 3.5 includes several new features, including

• Multi-threaded support
• Additional MPI-IO functions
• Various updates including
  • New configuration options and tests
  • Updated test suite
  • Updated build behavior

Please see the ChangeLog for additional changes.

• MPI installation
• libunwind : for collecting stack traces.
• binutils : for address to source translation
• glibc backtrace() can also be usef for stack tracing, but source line numbers may be inconsistent.

Several specific configuration flags can be using, as provided by ./configure -h. Standard configure flags, such as CC, can be used for specifying MPI compiler wrapper scripts.

Using mpiP is very simple. Because it gathers MPI information through the MPI profiling layer, mpiP is a link time library. That is, you don't have to recompile your application to use mpiP. Note that you might have to recompile to include the '-g' option. This is important if you want mpiP to decode the PC to a source code filename and line number automatically. mpiP will work without -g, but mileage may vary.

Link the mpiP library with an executable. The dependent libraries may need to be specified as well. If the link command includes the MPI library, order the mpiP library before the MPI library, as in -lmpiP -lmpi.

An uninstrumented executable may able to be instrumented at run time by setting the LD_PRELOAD environment variable, as in export LD_PRELOAD=[path to mpiP]/libmpiP.so. Preloading libmpiP can possibly interfere with the launcher and may need to be specified on the launch command, such as srun -n 2 --export=LD_PRELOAD=[path to mpiP]/libmpiP.so [executable].

The behavior of mpiP can be set at run time through the use of the following flags. Multiple flags can be delimited with spaces or commas.

For example, to set the callsite stack walking depth to 2 and the report print threshold to 10%, you simply need to define the mpiP string in your environment, as in any of the following examples:

$ export MPIP="-t 10.0 -k 2" (bash)

$ export MPIP=-t10.0,-k2 (bash)

$ setenv MPIP "-t 10.0 -k 2" (csh)

mpiP prints a message at initialization if it successfully finds the MPIP variable.

For more information on mpiP, please see the User Guide in the mpiP distribution.

Copyright (c) 2006, The Regents of the University of California. Produced at the Lawrence Livermore National Laboratory Written by Jeffery Vetter and Christopher Chambreau. UCRL-CODE-223450. All rights reserved.

This file is part of mpiP. For details, see http://llnl.github.io/mpiP.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

• Redistributions of source code must retain the above copyright notice, this list of conditions and the disclaimer below.

• Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the disclaimer (as noted below) in the documentation and/or other materials provided with the distribution.

• Neither the name of the UC/LLNL nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

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1. This notice is required to be provided under our contract with the U.S. Department of Energy (DOE). This work was produced at the University of California, Lawrence Livermore National Laboratory under Contract No. W-7405-ENG-48 with the DOE.

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