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

       dgmap, dgpart - compute static mappings and partitions in parallel

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

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

       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 options 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

       -bval  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.

       -copt  Choose  default  mapping	strategy  according  to	one or several
	      options 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.

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

	      -q     (for dgpart)

		     (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.

	      -rpnum Set root process for centralized files (default is	0).

	      -V     Display program version and copyright.

	      -vverb 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.

       At the time being (version 5.1),	dgmap cannot compute full static  map-
       pings  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.

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

	   $ mpirun -np	5 dgpart 7 brol.grf

       Run dgpart on 5 processing elements to partition	into 7 parts the  dis-
       tributed	  graph	  stored   on  graph  fragment	files  brol5-0.dgr  to
       brol5-4.dgr, and	save the  resulting  mapping  to  file  (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

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

       PT-Scotch user's	manual.

       Francois	Pellegrini <>

			      September	01, 2011		      dgmap(1)


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