sort under unicos

[Richard S. Freedman]

   This is a summary of improvements to the CRAY unicos [6.0] sort
that resulted from work done by a consultant at the Nasa Ames CCF.  Since I
received so many messages on this topic, I am posting this summary as a
reply.  The consultant said that the real problem is that unix sort was
written for a machine with virtual memory, and since the cray does not have
this feature the routine is very inefficient.

   Various people suggested that I use the SSD as the temporary disk
storage cache, but this is not possible because our SSD is currently
used as storage that mimics the scratch disk.  The only improvements possible
with a "quick fix" were:

        Assign the scratch disk as the temporary file space used by sort:
        [-T $TMP]
        recompile the sort routine so that it will use more memory when
        maximum memory is required [-y].

        reset various parameters inside sort:
        increased number of scratch files to 50
        set mthresh to 32
        set treez to 128
        set maximum memory to 2048 X 2048

   More improvement is possible according to the consultant, but this will
require time to implement the changes and more consultation with cray
consultants.

Richard Freedman
NASA Ames
freedman at amelia.nas.nasa.gov
         or
freedman at pan.arc.nasa.gov