gmap(1) Scotch user's manual gmap(1)NAME
gmap, gpart - compute static mappings and partitions sequentially
SYNOPSISgmap [options] [gfile] [tfile] [mfile] [lfile]
gpart [options] [nparts/pwght] [gfile] [mfile] [lfile]
DESCRIPTION
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 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, 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).
OPTIONS-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.
It is exclusive with the -m option.
-h Display some help.
-mstrat
Use sequential mapping strategy strat (see Scotch user's manual
for more information).
-q (for gpart)
-qpwght
(for gmap) Use the programs as graph clustering tools instead of
static mapping or graph partitioning tools. For gpart, the num‐
ber 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.
-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.
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 classi‐
cal 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 descrip‐
tion by using the amk_grf(1) command. In this case, the target descrip‐
tion will begin with the code name deco.
MAPPINGS
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 architec‐
ture (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.
EXAMPLES
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 ALSOamk_grf(1), acpl(1), gmtst(1), dgmap(1).
Scotch user's manual.
AUTHOR
Francois Pellegrini <francois.pellegrini@labri.fr>
September 01, 2011 gmap(1)
