dgmap [options] [gfile] [tfile] [mfile] [lfile] dgpart [options] [nparts] [gfile] [mfile] [lfile]
The dgpart program is a shortcut of dgmap for computing partitions of a source graph.
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.
$ mpirun -np 5 dgpart 7 brol.grf brol.mapRun 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
PT-Scotch user's manual.