Interpol

Interpol is an interposition library designed to trace and profile non-blocking MPI calls. This tools aims at evaluating the efficiency of MPI applications that use the non-blocking routines, specifically measuring the communication-computation overlap and pin pointing the critical code sections.

The library generates JSON traces of the intercepted MPI events which can thereafter be exploited using the project's provided GUI interface, Interpol Trace Analyzer, developed alongside the Interpol library.

Features

Currently, the library redefines the following MPI functions:

• MPI_Init/MPI_Init_thread;
• MPI_Finalize;
• MPI_Send/MPI_Recv;
• MPI_Isend/MPI_Irecv;
• MPI_Barrier/MPI_Ibarrier;
• MPI_Test;
• MPI_Wait.

At the moment, Interpol Trace Analyzer only support the MPI_COMM_WORLD communicator (support for user-defined communicators is planned in the future). Although only MPI_Init has been redefined, the library is thread-safe.

Currently, the library has been tested with the following MPI implementations:

• OpenMPI;
• MPICH;
• MPC.

Dependencies

For the library to work, please make sure that the following dependencies are installed on your system:

• Rust 2021 edition (v.1.56.0 or above, nightly channel is required);
• an MPI implementation and its provided patched compiler;
• GNU Make.

Building

To build the library, it is recommended to use the provided Makefile:

make

Optionnaly, you can install/uninstall it from your computer (/usr/lib/ by default):

sudo make install
sudo make uninstall

This will first call cargo to build the Rust back-end in release mode (automatically exported to the LD_LIBRARY_PATH environment variable). Then, it will compile the interposition library into a single .so file.

Usage

IMPORTANT NOTE: It is mandatory that you compile both the Interpol library and the MPI application that you want to trace with the same mpicc compiler! The MPI standard does not enforce any particular ABI. Therefore, if the library and your program are not compiled with the same MPI implementation, conflicts may cause the traced program or the library to crash or generate incorrect traces.

If you've installed the library, the command to preload it when running your MPI application should be:

LD_PRELOAD=libinterpol.so <MPICMD> -n <NB_PROC> <BINARY>

Otherwise, you need to provide the absolute path to the libinterpol.so file.

You can also check the documentation for the Rust back-end with the make doc command and run the unit tests with make test.