dgord(1) PT-Scotch user's manual dgord(1)NAMEdgord - compute sparse matrix orderings of graphs in parallel
SYNOPSISdgord [options] [gfile] [ofile] [lfile]
DESCRIPTION
The dgord program computes, in a parallel way, an ordering of a Scotch
source graph representing the pattern of some symmetric sparse matrix.
Source graph file gfile is either a centralized graph file, or a set of
files representing fragments of a distributed graph. The resulting
ordering is stored in file ofile. 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, dgord can
directly handle compressed graphs, both as input and output. A stream
is treated as compressed whenever its name is postfixed with a com‐
pressed file extension, such as in 'brol.grf.bz2' or '-.gz'. The com‐
pression formats which can be supported are the bzip2 format ('.bz2'),
the gzip format ('.gz'), and the lzma format ('.lzma', on input only).
dgord bases on implementations of the MPI interface to spread work
across the processing elements. It is therefore not likely to be run
directly, but instead through some launcher command such as mpirun.
OPTIONS-copt Choose default ordering 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.
-h Display some help.
-mmfile
Save column block mapping data to file mfile. Mapping data spec‐
ifies, for each vertex, the index of the column block to which
this vertex belongs.
-ostrat
Use parallel graph ordering strategy strat (see PT-Scotch user's
manual for more information).
-rpnum Set root process for centralized files (default is 0).
-ttfile
Save partitioning tree data to file tfile. Partitioning tree
data specifies, for each vertex, the index of the first vertex
of the parent block of the block to which the vertex belongs.
Altogether with the mapping data provided in file mfile, it
allows one to rebuild the separator tree of the nested dissec‐
tion process.
-V Display program version and copyright.
-vverb Set verbose mode to verb. It is a set of one of more characters
which can be:
s strategy information.
t timing information.
EXAMPLES
Run dgord on 5 processing elements to reorder matrix graph brol.grf and
save the resulting ordering to file brol.ord, using the default sequen‐
tial graph ordering strategy:
$ mpirun -np 5 dgord brol.grf brol.ord
Run dgord on 5 processing elements to reorder the distributed matrix
stored on graph fragment files brol5-0.dgr to brol5-4.dgr, and save the
resulting ordering to file brol.ord (see dgscat(1) for an explanation
of the '%p' and '%r' sequences in names of distributed graph frag‐
ments).
$ mpirun -np 5 dgord brol%p-%r.dgr brol.ord
SEE ALSOdgtst(1), dgscat(1), gmk_hy(1), gord(1).
PT-Scotch user's manual.
AUTHOR
Francois Pellegrini <francois.pellegrini@labri.fr>
February 14, 2011 dgord(1)
