HP XC System 4.x Software manual Modulefiles, Hp-Mpi, OpenMP, Pthreads, Quadrics Shmem

4.7.1.1 Modulefiles

The basics of your working environment are set up automatically by your system administrator during the installation of HP XC. However, your application development environment can be modified by means of modulefiles, as described in “Overview of Modules”.

There are modulefiles available that you can load yourself to further tailor your environment to your specific application development requirements. For example, the TotalView module is available for debugging applications. “Overview of Modules” provides instructions on how to list what modulefiles are available for you to load, and how load a modulefile.

If you encounter problems accessing tools or commands (and associated manpages), ensure that required modules are loaded on your system. If necessary, load required modules yourself, as described in “Overview of Modules”. Otherwise, contact your system administrator.

4.7.1.2 HP-MPI

With the HP XC system software, you can use the HP-MPIdistributed memory programming model for building and running parallel applications. In this model, all data is private to each process. All intercore communication within a parallel application is performed through calls to the HP-MPI message passing library. Even though support for applications that use a shared-memory programming model is not available at this time, individual cores within an application node can be used in the same application as separate HP-MPI tasks. Applications that are based on MPI, and currently run on Linux (or Linux compatible) systems, can be easily migrated to an HP XC cluster.

See the HP-MPI documentation for more information.

4.7.1.3 OpenMP

The OpenMP specification is a set of compiler directives that can be used to specify shared-memory parallelism in Fortran and C/C++ programs. Both Intel and Portland Group Fortran and C/C++ compilers support OpenMP.

Although OpenMP is designed for use on shared-memory architectures, OpenMP can be used on an HP XC system within a node.

OpenMP can be used alone, or in conjunction with HP-MPI. For information about compiling programs using OpenMP, see the OpenMP documentation.

4.7.1.4 Pthreads

POSIX Threads (Pthreads) is a standard library that programmers can use to develop portable threaded applications. Pthreads can be used in conjunction with HP-MPI on the HP XC system. Compilers from GNU, Intel and PGI provide a -pthreadswitch to allow compilation with the Pthread library.

Packages that link against Pthreads, such as MKL, require that the application is linked using the -pthreadoption. The Pthread option is invoked with the following compiler-specific switches:

GNU -pthread

Intel -pthread

PGI -lpgthread

For example:

$ mpicc object1.o ... -pthread -o myapp.exe

4.7.1.5 Quadrics SHMEM

The Quadrics implementation of SHMEM runs on HP XC systems with Quadrics switches. SHMEM is a collection of high-performance routines (that support a distributed-memory model) for data passing between parallel executables.

4.7 Developing Parallel Applications 43