AIPS HELP file for PARALLEL in 31DEC24

As of Thu Apr 25 23:10:24 2024

INPUTS

          The number of processors to be used for parallelized
          AIPS programs is given as the immediate argument.

HELP SECTION

PARALLEL
Type: Verb
Use:  PARALLEL(p) will interpret its immediate argument as the
      number of processors that will be used by AIPS tasks that
      have been enabled for parallel processing.  This will not
      have any effect on tasks that have not been specifically
      compiled to use multiple processors or on tasks that are
      already running.
         In general, large problems benefit from having more
      processors working on them but you may experience
      substantial slow-downs if you set p (the number of
      processors too large).  In preparing for a long run (which
      is where parallel processing is most worth while) it is
      often useful to select a small subset of your data that
      can be processed in a few minutes and experiment with
      different values of p to find the fastest option.  Task-
      specific explain files may give more detailed advice.
         The following rules of thumb may be helpful.
         - Keep p = 1 unless you are reasonably sure that
           parallel processing will help with the problem that
           you are dealing with.
         - If your machine has n processors limit p to n-1 so
           that one processor is free to handle the AIPS
           command-line processor and other functions (most
           parallel FORTRAN systems suffer badly if they have
           to share processors with other programs).
         - Reduce the number of processors if you are
           sharing a machine with other users.
      Special cases:
         PRINTER(0): (or no argument) show the current number
                     of processors that will be used by
                     parallel tasks.
Adverbs:  The immediate argument is the number of logical
      processors.
      No actual adverbs.

EXPLAIN SECTION