mpptest - test individual communication speeds
Test a single communication link by various methods.  The tests are 
combinations of
  Protocol: 
  -sync        Blocking sends/receives    (default)
  -async       NonBlocking sends/receives
  -force       Ready-receiver (with a null message)
  -persistant  Persistant communication (only with MPI)

  Message data:
  -cachesize n Perform test so that cached data is NOT reused

  Message pattern:
  -roundtrip   Roundtrip messages         (default)
  -head        Head-to-head messages
    
  Message test type:
  (if not specified, only communication tests run)
  -overlap     Overlap computation with communication (see -size)
  -overlapmsgsize nn
               Size of messages to overlap with is nn bytes.
  -bisect      Bisection test (all processes participate
  -bisectdist n Distance between processes
    
  Message sizes:
  -size start end stride                  (default 0 1024 32)
               Messages of length (start + i*stride) for i=0,1,... until
               the length is greater than end.
  -sizelist n1,n2,...
               Messages of length n1, n2, etc are used.  This overrides 
               -size
  -auto        Compute message sizes automatically (to create a smooth
               graph.  Use -size values for lower and upper range
  -autodx n    Minimum number of bytes between samples when using -auto
  -autorel d   Relative error tolerance when using -auto (0.02 by default)

  Number of tests
  -reps n      Number of times message is sent (default 1000)
  -autoreps    Compute the number of times a message is sent automatically
  -tgoal  d    Time that each test should take, in seconds.  Use with 
               -autoreps
  -rthresh d   Fractional threshold used to determine when minimum time
               has been found.  The default is 0.05.

  -gop [ options ]:

Collective Tests:
-dsum     : reduction (double precision)
-isum     : reduction (integer)
-sync     : synchronization
-colx     : collect with known sizes
-colxex   : collect with known sizes with exchange alg.
-scatter  : scatter
-bcast    : another name for -scatter

Collective test control:
-pset n-m            : processor set consisting of nodes n to m
Collective communication algorithms:
-rr n   : use a ready-receiver version for messages n bytes or longer
          (many operations do not yet have rr versions)
-ring   : use a ring algorithm
-tree   : use a tree algorithm
-line   : use a linear algorithm

Options for collective algorithms
-pkt len stride cnt : use packets of length len
-fast               : use a (possibly) contention-free tree

Output
  -cit         Generate data for CIt (default)
  -gnuplot     Generate data for GNUPLOT
  -givedy      Give the range of data measurements
  -fname filename             (default is stdout)
               (opened for append, not truncated)
  -noinfo      Do not generate plotter command lines or rate estimate
  -wx i n      windows in x, my # and total #
  -wy i n      windows in y, my # and total #
  -lastwindow  generate the wait/new page (always for 1 window)

Pattern (Neighbor) choices:
  -nbrring  - neighbors are +/- distance
  -nbrdbl   - neighbors are +/- 2**distance
  -nbrhc    - neighbors are hypercube
  -nbrshift - neighbors are + distance (wrapped)
