Subject:    -8- My decon job is taking forever.  What's wrong?
Date:  2 Jan 2001 18:00:00 PST

  Here are a couple of things to check:

    1) Check the header for your input data (as one of the first
       things it does, decon writes a summary of the header to the log
       file).  If the pixel spacings are invalid (not positive) or one
       of the wavelengths is invalid (not positive) that could be
       the cause.  You should kill the decon job, use EditHeader
       to correct the input data, and restart the job.

    2) The system could be spending most of its time paging chunks
       of memory to and from disk; this most frequently happens
       when deconvolving data sets which have large x, y, and
       z dimensions or when several memory intensive jobs are
       running at once.  On IRIX, use osview and check the amount
       of free memory (under the System Memory category) and the
       Wait Ratio percentages, if the free memory is low and
       the wait ratio percentages are high, then the entire system
       is struggling because there is not enough physical memory
       available for the applications currently running.  On Linux
       or OSF/1, you can use

            vmstat 10 10

       (check memory statistics every 10 seconds over 10 intervals)
       and pay attention to the pin/pout (OSF/1) or si/so (Linux)
       columns.  If these are high, then the system is paging.

       Depending on the situation, any of the following may be
       an appropriate solution:

         a) Run the job on a machine with more RAM.
         b) Run fewer jobs at once so that competition for memory
            is less fierce.
         c) The decon dialog has an option (the Special
            Parameters->Use minimal amount toggle) which will
            cause decon to demand less memory (roughly a factor
            of 3) and use a scratch file instead.  If the job is
            large enough to cause the machine to swap heavily,
            using this option can significantly improve the amount
            of time needed to perform the deconvolution.  The
            command-line option to force use of the scratch file
            is -nomem.