scotch_gmap man page

gmap, gpart — compute static mappings and partitions sequentially


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

gpart [options] [nparts] [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 shortcut of gmap for computing unweighted partitions of a source graph.

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).



Choose default mapping strategy according to one or several options among:

enforce load balance as much as possible.
privilege quality over speed (default).
privilege speed over quality.
enforce safety.
Display some help.
Use sequential mapping strategy strat (see Scotch user's manual for more information).
Display program version and copyright.

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

mapping information.
strategy information.
timing information.

Target Architectures

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, ... whgt-1.
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 'brol.map'.

$ gpart 7 brol.grf brol.map

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 'brol.map'. 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 - brol.map

See Also

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

Scotch user's manual.


Francois Pellegrini <francois.pellegrini@labri.fr>


Scotch user's manual August 03, 2010