Getting Started with Intel® MPI Library for Linux* OS

Intel® MPI Library is a multi-fabric message passing library that implements the Message Passing Interface, version 3.1 (MPI-3.1) specification. Use the library to develop applications that can run on multiple cluster interconnects.

Intel® MPI Library has the following features:

Scalability up to 340k processes
Low overhead, enables analyzing large amounts of data
MPI tuning utility for accelerating your applications
Interconnect independence and flexible runtime fabric selection

Intel® MPI Library is available as a standalone product and as part of the Intel® Parallel Studio XE Cluster Edition.

Product Contents

The product comprises the following main components:

Runtime Environment (RTO) includes the tools you need to run programs, including the scalable process management system (Hydra*), supporting utilities, shared (.so) libraries, and documentation.
Software Development Kit (SDK) includes all of the Runtime Environment components plus compilation tools, including compiler drivers such as mpiicc, include files and modules, static (.a) libraries, debug libraries, and test codes.

Besides the SDK and RTO components, Intel® MPI Library also includes Intel® MPI Benchmarks, which enable you to measure MPI operations on various cluster architectures and MPI implementations. For details, see the Intel® MPI Benchmarks User Guide.

Prerequisites

Before you start using Intel® MPI Library make sure to complete the following steps:

Source the mpivars.[c]sh script to establish the proper environment settings for the Intel® MPI Library. The script is located at <installdir>/compilers_and_libraries_<version>.<update>.<package>/linux/mpi/intel64/bin, where <installdir> is the Intel Parallel Studio XE installation directory (for example, /opt/intel).
Create a hostfile text file that lists the nodes in the cluster using one host name per line. For example:
```
clusternode1
clusternode2
```
Make sure the passwordless SSH connection is established among all nodes of the cluster. It ensures the proper communication of MPI processes among the nodes. To establish the connection, you can use the sshconnectivity.exp script located at <installdir>/parallel_studio_xe_<version>.<update>.<package>/bin.

After completing these steps, you are ready to use Intel® MPI Library.

For detailed system requirements, see the System Requirements section in Release Notes.

Building and Running MPI Programs

Compiling an MPI program

If you have the SDK component installed, you can build your MPI programs with Intel® MPI Library. Do the following:

Make sure you have a compiler in your PATH. To check this, run the which command on the desired compiler. For example:

$ which icc
/opt/intel/compilers_and_libraries_<version>.<update>.<package>/linux/bin/intel64/icc

Compile a test program using the appropriate compiler driver. For example:

$ mpiicc -o myprog <installdir>/test/test.c

Running an MPI program

Use the previously created hostfile and run your program with the mpirun command as follows:

$ mpirun -n <# of processes> -ppn <# of processes per node> -f ./hostfile ./myprog

For example:

$ mpirun -n 2 -ppn 1 -f ./hostfile ./myprog

The test program above produces output in the following format:

Hello world: rank 0 of 2 running on clusternode1
Hello world: rank 1 of 2 running on clusternode2

This output indicates that you properly configured your environment and Intel® MPI Library successfully ran the test MPI program on the cluster.

Key Features

Intel® MPI Library has the following major features:

MPI-1, MPI-2.2 and MPI-3.1 specification conformance
Intel® Xeon Phi™ processor support (formerly code named Knights Landing)
Support for any combination of the following interconnection fabrics:
- Shared memory
- Network fabrics with tag matching capabilities through Tag Matching Interface (TMI), such as Intel® True Scale Fabric, Infiniband*, Myrinet* and other interconnects
- Native InfiniBand* interface through OFED* verbs provided by Open Fabrics Alliance* (OFA*)
- OpenFabrics Interface* (OFI*)
- RDMA-capable network fabrics through DAPL*, such as InfiniBand* and Myrinet*
- Sockets, for example, TCP/IP over Ethernet*, Gigabit Ethernet*, and other interconnects
(SDK only) Support for Intel® 64 architecture Intel® MIC Architecture clusters using:
- Intel® C++ Compiler version 15.0 and higher
- Intel® Fortran Compiler version 15.0 and higher
- GNU* C, C++ and Fortran 95 compilers
(SDK only) C, C++, Fortran* 77, Fortran 90 language bindings and Fortran 2008 bindings
(SDK only) Dynamic linking

Troubleshooting

If you encounter problems when using Intel® MPI Library, go through the following general procedures to troubleshoot them:

Check system requirements and known issues in the Release Notes.
Check hosts accessibility. Run a simple non-MPI application (for example, hostname utility) on the problem hosts with mpirun. This check helps you reveal the environmental problem (for example, SSH is not configured properly), or connectivity problem (for example, unreachable hosts).
Run the MPI application with debug information enabled. To enable the debug information, set the environment variable I_MPI_DEBUG=6. You can also set a different debug level to get more detailed information. This action helps you find out the problem component.

See more details in the Troubleshooting section of the Developer Guide.

Training and Documentation

Resource	Description
Online Training	The online training site is an excellent resource for learning the Intel® MPI Library capabilities through various guides, videos, webinars, and more.
Release Notes	This page contains the most up-to-date information about the product, including: what's new, key features, system requirements and known limitations.
Online Documentation	This page provides links to all available Intel® MPI Library documents.

Legal Information

Intel, Xeon Phi, and the Intel logo are trademarks of Intel Corporation in the U.S. and/or other countries.

*Other names and brands may be claimed as the property of others.

Optimization Notice
Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice. Notice revision #20110804

Optimization Notice

Intel's compilers may or may not optimize to the same degree for non-Intel microprocessors for optimizations that are not unique to Intel microprocessors. These optimizations include SSE2, SSE3, and SSSE3 instruction sets and other optimizations. Intel does not guarantee the availability, functionality, or effectiveness of any optimization on microprocessors not manufactured by Intel. Microprocessor-dependent optimizations in this product are intended for use with Intel microprocessors. Certain optimizations not specific to Intel microarchitecture are reserved for Intel microprocessors. Please refer to the applicable product User and Reference Guides for more information regarding the specific instruction sets covered by this notice.

Notice revision #20110804