Basic HTML version of Foils prepared November 5 98

Foil 44 Java Rules for Floating Point

From Integration of Scientific and Technical Computing with Enterprise Information Systems: Gateway and IPSE ASC Dayton Ohio Invited Presentation -- October 29 98. by Geoffrey C. Fox
1 Java is particularly slow on floating point -- why?
  • Immature Compiler and library Technology
  • Does not Exploit optimally hardware on PowerPC and Intel platforms
    • Current Java rules optimized for SPARC architecture .....
  • Does not use well known compiler optimizations for blocking, unrolling, reorganizing expressions
2 Current Java rules imply that if careful (avoid indeterminate threads and use of JNI) Java not only runs everywhere but gets identical results everywhere
3 Need to study Reproducibility -- Performance Trade-offs
  • Maybe people have emphasized performance too much but you are not going to change their minds quickly -- should be tolerant of all perceived needs
  • Note current Java is both lower precision AND lower performance than other languages
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