Scotch domain decomposition. When run in parallel will collect the whole graph on to the master, decompose and send back. Use ptscotchDecomp for proper distributed decomposition. More...
Public Member Functions  
TypeName ("scotch")  
Runtime type information. More...  
scotchDecomp (const dictionary &decompositionDict)  
Construct given the decomposition dictionary and mesh. More...  
virtual  ~scotchDecomp () 
Destructor. More...  
virtual bool  parallelAware () const 
Is method parallel aware (i.e. does it synchronize domains across. More...  
virtual labelList  decompose (const polyMesh &mesh, const pointField &points, const scalarField &pointWeights) 
Return for every coordinate the wanted processor number. Use the. More...  
virtual labelList  decompose (const polyMesh &mesh, const labelList &agglom, const pointField ®ionPoints, const scalarField ®ionWeights) 
Return for every coordinate the wanted processor number. Gets. More...  
virtual labelList  decompose (const labelListList &globalCellCells, const pointField &cc, const scalarField &cWeights) 
Return for every coordinate the wanted processor number. Explicitly. More...  
Public Member Functions inherited from decompositionMethod  
TypeName ("decompositionMethod")  
Runtime type information. More...  
declareRunTimeSelectionTable (autoPtr, decompositionMethod, dictionary,(const dictionary &decompositionDict),(decompositionDict))  
decompositionMethod (const dictionary &decompositionDict)  
Construct given the decomposition dictionary. More...  
virtual  ~decompositionMethod () 
Destructor. More...  
label  nDomains () const 
virtual labelList  decompose (const pointField &points, const scalarField &pointWeights) 
Return for every coordinate the wanted processor number. More...  
virtual labelList  decompose (const pointField &) 
Like decompose but with uniform weights on the points. More...  
virtual labelList  decompose (const polyMesh &, const pointField &) 
Like decompose but with uniform weights on the points. More...  
virtual labelList  decompose (const polyMesh &mesh, const labelList &cellToRegion, const pointField ®ionPoints) 
Like decompose but with uniform weights on the regions. More...  
virtual labelList  decompose (const labelListList &globalCellCells, const pointField &cc) 
Like decompose but with uniform weights on the cells. More...  
void  setConstraints (const polyMesh &mesh, boolList &blockedFace, PtrList< labelList > &specifiedProcessorFaces, labelList &specifiedProcessor, List< labelPair > &explicitConnections) 
Helper: extract constraints: More...  
void  applyConstraints (const polyMesh &mesh, const boolList &blockedFace, const PtrList< labelList > &specifiedProcessorFaces, const labelList &specifiedProcessor, const List< labelPair > &explicitConnections, labelList &finalDecomp) 
Helper: apply constraints to a decomposition. This gives. More...  
virtual labelList  decompose (const polyMesh &mesh, const scalarField &cellWeights, const boolList &blockedFace, const PtrList< labelList > &specifiedProcessorFaces, const labelList &specifiedProcessor, const List< labelPair > &explicitConnections) 
labelList  decompose (const polyMesh &mesh, const scalarField &cWeights) 
Decompose a mesh. Apply all constraints from decomposeParDict. More...  
Additional Inherited Members  
Static Public Member Functions inherited from decompositionMethod  
static autoPtr< decompositionMethod >  New (const dictionary &decompositionDict) 
Return a reference to the selected decomposition method. More...  
static void  calcCellCells (const polyMesh &mesh, const labelList &agglom, const label nLocalCoarse, const bool global, CompactListList< label > &cellCells) 
Helper: determine (local or global) cellCells from mesh. More...  
static void  calcCellCells (const polyMesh &mesh, const labelList &agglom, const label nLocalCoarse, const bool parallel, CompactListList< label > &cellCells, CompactListList< scalar > &cellCellWeights) 
Helper: determine (local or global) cellCells and face weights. More...  
Protected Attributes inherited from decompositionMethod  
const dictionary &  decompositionDict_ 
label  nProcessors_ 
PtrList< decompositionConstraint >  constraints_ 
Optional constraints. More...  
Scotch domain decomposition. When run in parallel will collect the whole graph on to the master, decompose and send back. Use ptscotchDecomp for proper distributed decomposition.
Quoting from the Scotch forum, on the 20080822 10:09, Francois PELLEGRINI posted the following details:
RE: Graph mapping 'strategy' string Strategy handling in Scotch is a bit tricky. In order not to be confused, you must have a clear view of how they are built. Here are some rules: 1 Strategies are made up of "methods" which are combined by means of "operators". 2 A method is of the form "m{param=value,param=value,...}", where "m" is a single character (this is your first error: "f" is a method name, not a parameter name). 3 There exist different sort of strategies : bipartitioning strategies, mapping strategies, ordering strategies, which cannot be mixed. For instance, you cannot build a bipartitioning strategy and feed it to a mapping method (this is your second error). To use the "mapCompute" routine, you must create a mapping strategy, not a bipartitioning one, and so use stratGraphMap() and not stratGraphBipart(). Your mapping strategy should however be based on the "recursive bipartitioning" method ("b"). For instance, a simple (and hence not very efficient) mapping strategy can be : "b{sep=f}" which computes mappings with the recursive bipartitioning method "b", this latter using the FiducciaMattheyses method "f" to compute its separators. If you want an exact partition (see your previous post), try "b{sep=fx}". However, these strategies are not the most efficient, as they do not make use of the multilevel framework. To use the multilevel framework, try for instance: "b{sep=m{vert=100,low=h,asc=f}x}" The current default mapping strategy in Scotch can be seen by using the "vs" option of program gmap. It is, to date: r { job=t, map=t, poli=S, sep= ( m { asc=b { bnd= ( d{pass=40,dif=1,rem=1}  ) f{move=80,pass=1,bal=0.002491}, org=f{move=80,pass=1,bal=0.002491}, width=3 }, low=h{pass=10} f{move=80,pass=1,bal=0.002491}, type=h, vert=80, rat=0.8 }  m { asc=b { bnd= ( d{pass=40,dif=1,rem=1}  ) f{move=80,pass=1,bal=0.002491}, org=f{move=80,pass=1,bal=0.002491}, width=3 }, low=h{pass=10} f{move=80,pass=1,bal=0.002491}, type=h, vert=80, rat=0.8 } ) }
Given that this information was written in 2008, this example strategy will unlikely work asis with the more recent Scotch versions. Therefore, the steps for getting the current default strategy from within Scotch, is to do the following steps:
Edit the file system/decomposeParDict
and use the following settings:
method scotch; scotchCoeffs { writeGraph true; }
Run decomposePar
. For example, it will write a file named region0.grf
.
Now, instead of using gmap
, run gpart
with the following command structure to get the default strategy:
gpart \<nProcs\> vs \<grfFile\>
where:
writeGraph=true
, namely region0.grf
. numberOfSubdomains
defined in the dictionary file. At the end of the execution will be shown a long string, similar to the following example (complete line was cropped at [...]
):
S Strat=m{asc=b{width=3,bnd=d{pass=40,dif=1,rem=0}[...],type=h}
Edit the file system/decomposeParDict
once again and add the strategy
entry as exemplified:
method scotch; scotchCoeffs { // writeGraph true; strategy "m{asc=b{width=3,bnd=d{pass=40,dif=1,rem=0}[...],type=h}"; }
Finally, run decomposePar
once again, to at least test if it works as intended.
gpart
can be found in the current search path by adding the respective bin
folder from the Scotch installation, namely by running the following commands:source $(foamEtcFile config.sh/scotch) export PATH=$PATH:$SCOTCH_ARCH_PATH/bin
Definition at line 224 of file scotchDecomp.H.
scotchDecomp  (  const dictionary &  decompositionDict  ) 
Construct given the decomposition dictionary and mesh.
Definition at line 80 of file dummyScotchDecomp.C.

inlinevirtual 
Destructor.
Definition at line 270 of file scotchDecomp.H.
TypeName  (  "scotch"  ) 
Runtime type information.

inlinevirtual 
Is method parallel aware (i.e. does it synchronize domains across.
proc boundaries)
Implements decompositionMethod.
Definition at line 276 of file scotchDecomp.H.
References decompositionMethod::decompose(), mesh, and points.

virtual 
Return for every coordinate the wanted processor number. Use the.
mesh connectivity (if needed) Weights get normalised with minimum weight and truncated to convert into integer so e.g. 3.5 is seen as 3. The overall sum of weights might otherwise overflow.
Implements decompositionMethod.
Definition at line 91 of file dummyScotchDecomp.C.
References Foam::exit(), Foam::FatalError, FatalErrorInFunction, notImplementedMessage, and List< label >::null().

virtual 
Return for every coordinate the wanted processor number. Gets.
passed agglomeration map (from fine to coarse cells) and coarse cell location. Can be overridden by decomposers that provide this functionality natively. See note on weights above.
Reimplemented from decompositionMethod.
Definition at line 105 of file dummyScotchDecomp.C.
References Foam::exit(), Foam::FatalError, FatalErrorInFunction, notImplementedMessage, and List< label >::null().

virtual 
Return for every coordinate the wanted processor number. Explicitly.
provided mesh connectivity. The connectivity is equal to mesh.cellCells() except for
Implements decompositionMethod.
Definition at line 120 of file dummyScotchDecomp.C.
References Foam::exit(), Foam::FatalError, FatalErrorInFunction, notImplementedMessage, and List< label >::null().