Thomas Zeiser

Some comments by Thomas Zeiser about HPC@RRZE and other things

Content

Using NEC SX-8 at HLRS

The NEC SX-8 is a nice vector machine. The compilers produce a lot of compile time information concerning optimization and vectorization.

Some unsorted notes to make life easier…

  • NEC SX series uses big endian, the “fronend system”, an Itanium2 system (NEC TX-7) however little endian. Fortran programmers have several options for automatic conversion of unformated data:
    • on the IA64 side (for executables generated with the Intel compiler): setenv F_UFMTENDIAN=big makes your program read/write big endian data
    • on the NEC SX side: setenv F_UFMTENDIAN u[,u...] to read/write little endian data; u[,u,...] are the units to convert.
  • by default, the NEC SX-8 Fortran runtime library does not read/write unformated records which are larger than 2 GB. setenv F_EXPRCW u,[u,...] enables processing of file records that are over 2GB in length. When this environment variable is specified, both record control words and End of Record markers are expanded to 8-byte quantities. F_EXPRCW and F_UFMTENDIAN cannot be used for the same unit.