Programming on Seaborg

The programming environment on the SP is similar to that found on most UNIX platforms. However, to ensure that all the machine's memory is made available to your programs, see Memory Management on the SP.

Compilers

IBM Compilers

• IBM XL Fortran
• IBM C/C++

Parallel programming is typically accomplished using IBM's MPI library, but the IBM compilers also support OpenMP. A Java compiler is also available.

Third-Party Compilers

• Portland Group High Performance Fortran (Limited to 128 tasks.)
• KAI C++ compiler (Product discontinued, but still available on Seaborg.)
• KAP/Pro OpenMP Toolset (Product discontinued, but still available on Seaborg.)
• GNU gcc, g++, g77

Parallel Programming

• IBM SP Parallel Scaling Overview

Most codes run on seaborg use the MPI library to communicate data between nodes. See MPI Resources for more information.

OpenMP directives can be used to create parallel threads of execution in a shared-memory environment, which translates to single node on the NERSC SP. OpenMP and MPI constructs may be mixed within a single program. See Using OpenMP on Seaborg.

High Performance Fortran programs can be compiled with the Portland Group's HPF compiler.

Debugging and Optimization

A number of tools facilitate debugging and profiling code. Much optimization can be accomplished with the proper IBM Compiler Optimization Flags. A detailed tuning guide from IBM is available as a pdf file: Power 3 Introduction and Tuning Guide.

Tutorials and How-To's

• Debugging strategies and tips
• Using the Totalview debugger on Seaborg
• Guidance on selecting math libraries on Seaborg
• IBM compiler optimization flags
• hpmcount and poe+ on Seaborg (performance measuring tools)

Programming Libraries

A rich set of mathematical, visualization, I/O, and other libraries are available on Seaborg.