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dgmap(1)                    PT-Scotch user's manual                   dgmap(1)

NAME
       dgmap, dgpart - compute static mappings and partitions in parallel

SYNOPSIS
       dgmap [options] [gfile] [tfile] [mfile] [lfile]

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

DESCRIPTION
       The dgmap program computes, in a parallel way, a static mapping of a
       source graph onto a target graph.

       The dgpart program is a simplified interface to dgmap, 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, dgmap only accepts variable-sized target architectures.

       Source graph file gfile is either a centralized graph file, or a set of
       files representing fragments of a distributed graph. For dgmap, 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. See gmap(1)
       for a description of target architectures. 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, dgmap and
       dgpart 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).

       dgmap and dgpart base on implementations of the MPI interface to spread
       work across the processing elements. They are therefore not likely to
       be run directly, but instead through some launcher command such as
       mpirun.

OPTIONS
       -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.

              x      enforce scalability.

              It is exclusive with the -m option.

              -h     Display some help.

              -m?strat
                     Use parallel mapping strategy strat (see PT-Scotch user's
                     manual for more information).

              -q     (for dgpart)

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

              -r?pnum
                     Set root process for centralized files (default is 0).

              -V     Display program version and copyright.

              -v?verb
                     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.

NOTE
       At the time being (version 5.1), dgmap cannot compute full static
       mappings as gmap(1) does, but only partitions (that is, mappings onto
       unweighted or weighted complete graphs). Target architectures other
       than the 'cmplt' and 'wcmplt' ones will lead to an error message.

EXAMPLES
       Run dgpart on 5 processing elements to compute a partition into 7 parts
       of graph brol.grf and save the resulting ordering to file brol.map.

           $ mpirun -np 5 dgpart 7 brol.grf brol.map

       Run dgpart on 5 processing elements to partition into 7 parts the
       distributed graph stored on graph fragment files brol5-0.dgr to
       brol5-4.dgr, and save the resulting mapping to file brol.map (see
       dgscat(1) for an explanation of the '%p' and '%r' sequences in names of
       distributed graph fragments).

           $ mpirun -np 5 dgpart 7 brol%p-%r.dgr brol.map

SEE ALSO
       dgtst(1), dgscat(1), amk_grf(1), acpl(1), gmap(1), gmtst(1).

       PT-Scotch user's manual.

AUTHOR
       Francois Pellegrini <francois.pellegrini@labri.fr>

                               September 1, 2011                      dgmap(1)