EMPI: Enhanced Message Passing Interface in Modern C++

About

EMPI is a C++ library that aims to enhance the MPI programming model's interface while providing competitive performance to OpenMPI. Its objective is to provide a more modern and straightforward interface to MPI while exploiting C++ language features to reduce programming errors and improve performance. It is developed using C++20, exploiting several modern C++ features.

CAVEAT: EMPI is highly experimental and its interface and features will probably change frequently

EMPI Requirements

EMPI is written in C++20, so a valid C++20 compiler (gcc 12 is recommended) alongside with Cmake version 3.0 are required. EMPI is shipped with a customized OpenMPI implementation, which is required to exploit the best performance. However, EMPI works with a vanilla OpenMPI as well, in case you don't want to compile the customized OpenMPI on your own. To do so, disable the unchecked function in the CMake configuring phase when building yout application with the flag -DENABLE_UNCHECKED_FUNCTION=OFF.
However, to benefit the maximum performance, it is suggested to compile with our customized OMPI.

Building EMPI examples

bash cd empi mkdir build cd build cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=$WORKSPACE/deps/openmpi/bin/mpicxx -DCMAKE_CXX_FLAGS='-O3 -ffast-math -march=native -I$WORKSPACE/deps/openmpi/include' make -j

Building LULESH

LULESH is placed under empi/benchmarks/LULESH. It uses the CMake variable -DWITH_MPI=[1|0] to enable the MPI implementation, and a variable to enable EMPI -DUSE_EMPI=[1|0].
To build LULESH using EMPI, type: bash cd $WORKSPACE/empi/benchmarks/LULESH mkdir build cd build cmake .. -DCMAKE_BUILD_TYPE=Release -DCMAKE_CXX_COMPILER=$WORKSPACE/deps/openmpi/bin/mpicxx -DCMAKE_CXX_FLAGS='-O3 -ffast-math -march=native -I$WORKSPACE/deps/openmpi/include' -DWITH_MPI=1 -DUSE_EMPI=1 -DEMPI_PATH=$WORKSPACE/empi/include make -j

Examples

The examples scripts are developed with the following dependencies:

• Python 3.8.10
  • Command
  • argparse

You can install the requirements with: bash pip3 install -r empi/scripts/requirements.txt

Under empi/scripts/ you will find 3 python scripts: - minibench.py
- vibrating_string.py
- lulesh.py

minibench.py, vibrating_string.py, and lulesh.py launch the related applications and takes a number of command line arguments to customize each run.

They provide a series of command line parameteres to configure the benchmark's execution. Type python [minibench.py | lulesh.py | vibrating_string.py] --help to have a deeper look to the possible options.

For example, to run all the microbenchmarks with: - 4 processors --num_proc=4 - 4 bytes message size --size=2 - 10 inner iterations per benchmark --app_iter=10 - 20 outer repetitions per benchmark (per mpirun: how many times do you want to run mpirun and report their average) --app_restart=20 - root permissions (if you are root) - Default dependencies path
bash python3 minibench.py --num_proc=4 --size=2 --app_iter=10 --app_restart=20 --root

Cite this work

If you use this software, please cite it as below. Link to the paper ``` @INPROCEEDINGS{10171546, author={Beni, Majid Salimi and Crisci, Luigi and Cosenza, Biagio}, booktitle={2023 IEEE/ACM 23rd International Symposium on Cluster, Cloud and Internet Computing (CCGrid)}, title={EMPI: Enhanced Message Passing Interface in Modern C++}, year={2023}, volume={}, number={}, pages={141-153}, keywords={Multiprotocol label switching;Message passing;Computational modeling;Semantics;C++ languages;Computer architecture;Programming;Message Passing Interface (MPI);Modern C++;Programming Models;High Performance Computing}, doi={10.1109/CCGrid57682.2023.00023}}

```