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Foil 17 Comments on Parallel Input/Output - II

From CPS615-Initial Lecture on MPI ending with discussion of basic MPI_SEND Delivered Lectures of CPS615 Basic Simulation Track for Computational Science -- 31 October 96. by Geoffrey C. Fox *
Secs 148.3
Today, memory costs have declined and ALL mainstream MIMD distributed memory machines whether clusters of workstations or integrated systems such as T3D/ Paragon/ SP-2 have enough memory on each node to run UNIX
Thus printf today means typically that the node on which it runs will stick it out on "standard output" file for that node
  • However this is implementation dependent
  • e.g. If you want a stream of output with information in order
    • Say that from node 0, then node 1, then node 2 etc.
    • This was default on old Caltech machines but
  • In general you need to communicate information from nodes 1 to N-1 to node 0 and let node 0 sort it and output in required order
New MPI-IO initiative will link I/O to MPI in a standard fashion



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