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gmap(1)                      Scotch user's manual                      gmap(1)

       gmap, gpart - compute static mappings and partitions sequentially

       gmap [options] [gfile] [tfile] [mfile] [lfile]

       gpart [options] [nparts/pwght] [gfile] [mfile] [lfile]

       The gmap program computes, in a sequential way, a static mapping of a
       source graph onto a target graph.

       The gpart program is a simplified interface to gmap, which performs
       graph partitioning instead of static mapping. Consequently, the desired
       number of parts has to be provided, in lieu of the target architecture.
       When using the program for graph clustering, the number of parts turns
       into maximum cluster weight.

       The -b and -c option?s allow the user to set preferences on the
       behavior of the mapping strategy which is used by default. The -m
       option allows the user to define a custom mapping strategy.

       The -q option turns the programs into graph clustering programs. In
       this case, gmap only accepts variable-sized target architectures.

       Source graph file gfile can only be a centralized graph file. For gmap,
       the target architecture file tfile describes either algorithmically-
       coded topologies such as meshes and hypercubes, or decomposition-
       defined architectures created by means of the amk_grf(1) program. The
       resulting mapping is stored in file mfile. Eventual logging information
       (such as the one produced by option -v) is sent to file lfile. When
       file names are not specified, data is read from standard input and
       written to standard output. Standard streams can also be explicitely
       represented by a dash '-'.

       When the proper libraries have been included at compile time, gmap and
       gpart can directly handle compressed graphs, both as input and output.
       A stream is treated as compressed whenever its name is postfixed with a
       compressed file extension, such as in 'brol.grf.bz2' or '-.gz'. The
       compression formats which can be supported are the bzip2 format
       ('.bz2'), the gzip format ('.gz'), and the lzma format ('.lzma', on
       input only).

       -b?val Set maximum load imbalance ratio for graph partitioning or
              static mapping. When programs are used as clustering tools, this
              parameter sets the maximum load imbalance ratio for recursive
              bipartitions. Exclusive with the -m option.

       -c?opt Choose default mapping strategy according to one or several
              option?s among:

              b      enforce load balance as much as possible.

              q      privilege quality over speed (default).

              s      privilege speed over quality.

              t      enforce safety.

              It is exclusive with the -m option.

       -h     Display some help.

              Use sequential mapping strategy strat (see Scotch user's manual
              for more information).

       -q     (for gpart)

              (for gmap) Use the programs as graph clustering tools instead of
              static mapping or graph partitioning tools. For gpart, the
              number of parts will become the maximum cluster weight. For
              gmap, this number pwght has to be passed after the option.

       -V     Display program version and copyright.

              Set verbose mode to verb. It is a set of one of more characters
              which can be:

              m      mapping information.

              s      strategy information.

              t      timing information.

       Target architectures represent graphs onto which source graphs are
       mapped. In order to speed-up the obtainment of target architecture
       topological properties during the computation of mappings, some
       classical topologies are algorithmically coded into the mapper itself.
       These topologies are consequently simply defined by their code name,
       followed by their dimensional parameters:

       cmplt dim
              unweighted complete graph of size dim.

       cmpltw dim w0 w1 ... wdim-1
              weighted complete graph of size size and of respective loads w0,
              w1, ..., wdim-1.

       hcub dim
              hypercube of dimension dim.

       leaf hgt n0 w0 ... nhgt-1 whgt-1
              tree-leaf graph of height hgt with (n0 times n1 times ...
              nhgt-1) vertices, with inter-cluster link weights of w0, w1, ...

       mesh2D dimX dimY
              2D mesh of dimX times dimY nodes.

       mesh3D dimX dimY dimZ
              23 mesh of dimX times dimY times dimZ nodes.

       torus2D dimX dimY
              2D torus of dimX times dimY nodes.

       torus3D dimX dimY dimZ
              3D torus of dimX times dimY times dimZ nodes.

       Other target topologies can be created from their source graph
       description by using the amk_grf(1) command. In this case, the target
       description will begin with the code name deco.

       Mappings are represented by as many lines as there are vertices in the
       source graph. Each of these lines is made of two figures: the number of
       the vertex (or its label if source graph vertices are labeled) and the
       index of the target vertex to which it has been assigned. Target vertex
       indices range from 0 to the number of vertices in the target
       architecture (that is, the number of parts) minus one.

       This block of lines is always preceded by the number of such lines. In
       most cases, since full mappings are requested, the number of lines is
       equal to the number of vertices in the source graph.

       Run gpart to compute a partition into 7 parts of graph 'brol.grf' and
       save the resulting ordering to file ''.

           $ gpart 7 brol.grf

       Run gmap to compute a partition, into 3 parts of respective weights 1,
       2 and 4, of graph 'brol.grf' and save the resulting mapping to file
       ''. The dash '-' standard file name is used so that the target
       architecture description is read from the standard input, through the
       pipe, as provided by the 'echo' shell command.

           $ echo "cmpltw 3 1 2 4" | gmap brol.grf -

       amk_grf(1), acpl(1), gmtst(1), dgmap(1).

       Scotch user's manual.

       Francois Pellegrini <>

                               September 1, 2011                       gmap(1)


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