Nektar::LibUtilities::MeshPartitionScotch Class Reference

#include <MeshPartitionScotch.h>

Inheritance diagram for Nektar::LibUtilities::MeshPartitionScotch:

Collaboration diagram for Nektar::LibUtilities::MeshPartitionScotch:

Public Member Functions
	MeshPartitionScotch (const SessionReaderSharedPtr &pSession)
virtual	~MeshPartitionScotch ()
Public Member Functions inherited from Nektar::LibUtilities::MeshPartition
	MeshPartition (const SessionReaderSharedPtr &pSession)
virtual	~MeshPartition ()
void	PartitionMesh (int nParts, bool shared=false, bool overlapping=false)
void	WriteLocalPartition (SessionReaderSharedPtr &pSession)
void	WriteAllPartitions (SessionReaderSharedPtr &pSession)
void	PrintPartInfo (std::ostream &out)
void	GetCompositeOrdering (CompositeOrdering &composites)
void	GetBndRegionOrdering (BndRegionOrdering &composites)
void	GetElementIDs (const int procid, std::vector< unsigned int > &tmp)

Static Public Member Functions
static MeshPartitionSharedPtr	create (const SessionReaderSharedPtr &pSession)
	Creates an instance of this class. More...

Static Public Attributes
static std::string	className
	Name of class. More...
static std::string	cmdSwitch = SessionReader::RegisterCmdLineFlag("use-scotch","","Use Scotch for mesh partitioning.")

Private Member Functions
virtual void	PartitionGraphImpl (int &nVerts, int &nVertConds, Nektar::Array< Nektar::OneD, int > &xadj, Nektar::Array< Nektar::OneD, int > &adjcy, Nektar::Array< Nektar::OneD, int > &vertWgt, Nektar::Array< Nektar::OneD, int > &vertSize, int &nparts, int &volume, Nektar::Array< Nektar::OneD, int > &part)
void	PartGraphVKway (const SCOTCH_Num *const n, const SCOTCH_Num *const xadj, const SCOTCH_Num *const adjncy, const SCOTCH_Num *const vwgt, const SCOTCH_Num *const vsize, const SCOTCH_Num *const wgtflag, const SCOTCH_Num *const numflag, const SCOTCH_Num *const nparts, const SCOTCH_Num *const options, SCOTCH_Num *const volume, SCOTCH_Num *const part)
int	PartGraph2 (const SCOTCH_Num *const n, const SCOTCH_Num *const xadj, const SCOTCH_Num *const adjncy, const SCOTCH_Num *const vwgt, const SCOTCH_Num *const adjwgt, const SCOTCH_Num *const numflag, const SCOTCH_Num *const nparts, SCOTCH_Num *const part, SCOTCH_Num flagval, double kbalval)

Detailed Description

Definition at line 49 of file MeshPartitionScotch.h.

Constructor & Destructor Documentation

Nektar::LibUtilities::MeshPartitionScotch::MeshPartitionScotch

(

const SessionReaderSharedPtr &

pSession

)

Definition at line 55 of file MeshPartitionScotch.cpp.

        : MeshPartition(pSession)
    {

    }

Nektar::LibUtilities::MeshPartitionScotch::~MeshPartitionScotch ( )

virtual

Definition at line 61 of file MeshPartitionScotch.cpp.

    {

    }

Member Function Documentation

static MeshPartitionSharedPtr Nektar::LibUtilities::MeshPartitionScotch::create ( const SessionReaderSharedPtr &  pSession )

inlinestatic

Creates an instance of this class.

Definition at line 53 of file MeshPartitionScotch.h.

References Nektar::MemoryManager< DataType >::AllocateSharedPtr().

            {
                return MemoryManager<MeshPartitionScotch>
                                                ::AllocateSharedPtr(pSession);
            }

int Nektar::LibUtilities::MeshPartitionScotch::PartGraph2 ( const SCOTCH_Num *const  n, const SCOTCH_Num *const  xadj, const SCOTCH_Num *const  adjncy, const SCOTCH_Num *const  vwgt, const SCOTCH_Num *const  adjwgt, const SCOTCH_Num *const  numflag, const SCOTCH_Num *const  nparts, SCOTCH_Num *const  part, SCOTCH_Num  flagval, double  kbalval  )

private

Definition at line 227 of file MeshPartitionScotch.cpp.

Referenced by PartGraphVKway().

    {
        // Scotch graph object to interface with libScotch
        SCOTCH_Graph        grafdat;
        SCOTCH_Strat        stradat;
        SCOTCH_Num          baseval;
        SCOTCH_Num          vertnbr;
        int                 o;

        SCOTCH_graphInit (&grafdat);

        baseval = *numflag;
        vertnbr = *n;

        o = 1; // Assume something will go wrong
        if (SCOTCH_graphBuild (&grafdat, baseval, vertnbr, xadj, xadj + 1,
                               vwgt, NULL, xadj[vertnbr] - baseval, adjncy,
                               adjwgt) == 0) {
            SCOTCH_stratInit          (&stradat);
            SCOTCH_stratGraphMapBuild (&stradat, flagval, *nparts, kbalval);
#ifdef SCOTCH_DEBUG_ALL
            // TRICK: next instruction called only if graph is consistent
            if (SCOTCH_graphCheck (&grafdat) == 0)
#endif /* SCOTCH_DEBUG_ALL */
                o = SCOTCH_graphPart (&grafdat, *nparts, &stradat, part);
            SCOTCH_stratExit (&stradat);
        }
        SCOTCH_graphExit (&grafdat);

        if (o != 0)
            return (1);

        if (baseval != 0) { // MeTiS part array is based, Scotch is not
            SCOTCH_Num          vertnum;

            for (vertnum = 0; vertnum < vertnbr; vertnum ++)
                part[vertnum] += baseval;
        }

        return (0);
    }

void Nektar::LibUtilities::MeshPartitionScotch::PartGraphVKway ( const SCOTCH_Num *const  n, const SCOTCH_Num *const  xadj, const SCOTCH_Num *const  adjncy, const SCOTCH_Num *const  vwgt, const SCOTCH_Num *const  vsize, const SCOTCH_Num *const  wgtflag, const SCOTCH_Num *const  numflag, const SCOTCH_Num *const  nparts, const SCOTCH_Num *const  options, SCOTCH_Num *const  volume, SCOTCH_Num *const  part  )

private

Communication volume of current vertex

Definition at line 101 of file MeshPartitionScotch.cpp.

References PartGraph2().

Referenced by PartitionGraphImpl().

    {
        SCOTCH_Num          baseval;
        const SCOTCH_Num *  vwgt2;
        const SCOTCH_Num *  vsize2;
        SCOTCH_Num          vsizval; /// Communication volume of current vertex
        SCOTCH_Num          vertnbr;
        SCOTCH_Num          vertnum;
        SCOTCH_Num          edgenum;
        const SCOTCH_Num *  edgetax;
        const SCOTCH_Num *  parttax;
        SCOTCH_Num *        nghbtab;
        SCOTCH_Num                  commvol;

        vsize2  = ((*wgtflag & 1) != 0) ? vsize : NULL;
        vwgt2   = ((*wgtflag & 2) != 0) ? vwgt  : NULL;
        baseval = *numflag;
        vertnbr = *n;
        edgetax = adjncy - baseval;

        // If no communication load   data provided
        if (vsize2 == NULL) {
            if (PartGraph2 (n, xadj, adjncy, vwgt2, NULL, numflag, nparts,
                            part, SCOTCH_STRATDEFAULT, 0.01) != 0)
                return;
        }

        // Will have to turn communication volumes into edge loads
        else {
            const SCOTCH_Num *  vsiztax;
            SCOTCH_Num          edgenbr;
            SCOTCH_Num *        edlotax;
            int                 o;

            edgenbr = xadj[vertnbr] - baseval;
            if ((edlotax =
                 (SCOTCH_Num*) malloc (edgenbr * sizeof (SCOTCH_Num))) == NULL)
            {
                return;
            }

            edlotax -= baseval; // Base access to edlotax
            vsiztax  = vsize2 - baseval;

            // Un-based scan of vertex array xadj
            for (vertnum = 0, edgenum = baseval;
                    vertnum < vertnbr; vertnum ++) {
                SCOTCH_Num      vsizval; // Communication size of current vertex
                SCOTCH_Num      edgennd;

                vsizval = vsize2[vertnum];
                // Based traversal of edge array adjncy
                for (edgennd = xadj[vertnum + 1];
                     edgenum < edgennd;
                     edgenum ++) {

                    SCOTCH_Num  vertend; // Based end vertex number

                    vertend = edgetax[edgenum];
                    edlotax[edgenum] = vsizval + vsiztax[vertend];
                }
            }

            o = PartGraph2 (n, xadj, adjncy, vwgt2, edlotax + baseval, numflag,
                            nparts, part, SCOTCH_STRATDEFAULT, 0.01);

            free (edlotax + baseval);

            if (o != 0)
                return;
        }

        if ((nghbtab =
             (SCOTCH_Num*) malloc (*nparts * sizeof (SCOTCH_Num))) == NULL)
        {
            return;
        }

        memset (nghbtab, ~0, *nparts * sizeof (SCOTCH_Num));

        parttax = part - baseval;
        vsizval = 1; // Assume no vertex communication sizes

        // Un-based scan of vertex array xadj
        for (vertnum = 0, edgenum = baseval, commvol = 0;
                vertnum < vertnbr; vertnum ++) {
            SCOTCH_Num      partval;
            SCOTCH_Num      edgennd;

            partval = part[vertnum];
            nghbtab[partval] = vertnum; // Do not count local neighbors in
                                        // communication volume
            if (vsize2 != NULL)
                vsizval = vsize2[vertnum];

            // Based traversal of edge array adjncy
            for (edgennd = xadj[vertnum + 1]; edgenum < edgennd; edgenum ++) {
                SCOTCH_Num  vertend; // Based end vertex number
                SCOTCH_Num  partend;

                vertend = edgetax[edgenum];
                partend = parttax[vertend];

                // If first neighbor in this part set part as accounted for
                if (nghbtab[partend] != vertnum) {
                    nghbtab[partend] = vertnum;
                    commvol += vsizval;
                }
            }
        }
        *volume = commvol;

        free (nghbtab);
    }

void Nektar::LibUtilities::MeshPartitionScotch::PartitionGraphImpl ( int &  nVerts, int &  nVertConds, Nektar::Array< Nektar::OneD, int > &  xadj, Nektar::Array< Nektar::OneD, int > &  adjcy, Nektar::Array< Nektar::OneD, int > &  vertWgt, Nektar::Array< Nektar::OneD, int > &  vertSize, int &  nparts, int &  volume, Nektar::Array< Nektar::OneD, int > &  part  )

privatevirtual

Implements Nektar::LibUtilities::MeshPartition.

Definition at line 66 of file MeshPartitionScotch.cpp.

References PartGraphVKway().

    {
        int wgtflag = 0;
        int *vwgt = 0;
        int *vsize = 0;
        if (vertWgt.num_elements() > 0)
        {
            wgtflag += 1;
            vwgt = &vertWgt[0];
        }
        if (vertSize.num_elements() > 0)
        {
            wgtflag += 2;
            vsize = &vertSize[0];
        }
        int numflag = 0;
        // number of balancing conditions (size of vertex multi-weight)
        int options[5];
        options[0] = 0;

        PartGraphVKway(&nVerts, &xadj[0], &adjcy[0], vwgt, vsize,
                            &wgtflag, &numflag, &nparts, options, &volume,
                            &part[0]);
    }

Member Data Documentation

std::string Nektar::LibUtilities::MeshPartitionScotch::className

static

Initial value:

= GetMeshPartitionFactory().RegisterCreatorFunction(
            "Scotch",
            MeshPartitionScotch::create,
            "Partitioning using the Scotch library.")

Name of class.

Definition at line 61 of file MeshPartitionScotch.h.

std::string Nektar::LibUtilities::MeshPartitionScotch::cmdSwitch = SessionReader::RegisterCmdLineFlag("use-scotch","","Use Scotch for mesh partitioning.")

static

Definition at line 62 of file MeshPartitionScotch.h.