Coding Considerations

Coding Considerations ii Intel ® Solution Services is Intel Corporation's worldwide professional services organization, helping enterprise companies capitalize on the full value of Intel architecture through consulting focused on architecture transitions. Backed by the largest silicon manufacturing company and one of the largest e-Business corporations in the world, Intel Solution Services uses its foremost expertise in Intel architecture and next generation technologies, as well as its relationships with key industry alliances, to design cost-effective, leading-edge solutions that help deliver superior business results. Our services are available through on-site consulting, as well as at Intel Solution Centers located worldwide. The Intel Solution Centers are state-of-the-art environments for designing and testing high-performance solutions using Intel's best-known methods and technologies. Performance tests and ratings are measured using specific computer systems and/or components and reflect the approximate performance of Intel products as measured by those tests. Any difference in system hardware or software design or configuration may affect actual performance. Buyers should consult other sources of information to evaluate the performance of systems or components they are considering purchasing. For more information on performance tests and on the performance of Intel products, reference Intel, the Intel logo, Itanium and VTune are trademarks or registered trademarks of Intel Corporation or its subsidiaries in the United States and other countries. *Other names and brands may be claimed as the property of others. Abstract All computer programs can benefit from specific tuning efforts aimed at extracting maximum performance on any given processor architecture. While it is relatively easy to derive peak performance values from the characteristics of the architecture and the implementation, it is difficult to approach that peak performance without extensive experience in tuning applications. Mature compilers can intuitively make many decisions. Yet " out-of-the-box " does not mean " black-box " for even mature compilers, and developers should be aware of what is going on behind the scenes. Developers still need to know how to evaluate what theoretical maximum may be and what should be done in the source code to encourage the compiler to generate close-to-theoretical maximum code. This paper provides a distillation of the most applicable techniques for tuning numerically-intensive codes on Intel ® Itanium ® architecture. It may repeat some traditional coding techniques, but primarily it highlights a different angle in high-performance computing practices. It explores issues around mature compilers, with the goal of achieving near-to-optimal theoretical scheduling. It explains how the …