MEDCoupling::OverlapDEC Class Reference

Inheritance diagram for MEDCoupling::OverlapDEC:

Collaboration diagram for MEDCoupling::OverlapDEC:

Public Member Functions
void	attachSourceLocalField (ICoCo::MEDDoubleField *field)
void	attachSourceLocalField (MEDCouplingFieldDouble *field)
void	attachSourceLocalField (ParaFIELD *field, bool ownPt=false)
void	attachTargetLocalField (ICoCo::MEDDoubleField *field)
void	attachTargetLocalField (MEDCouplingFieldDouble *field)
void	attachTargetLocalField (ParaFIELD *field, bool ownPt=false)
void	debugPrintWorkSharing (std::ostream &ostr) const
ProcessorGroup *	getGroup ()
bool	isInGroup () const
	OverlapDEC (const std::set< int > &procIds, const MPI_Comm &world_comm=MPI_COMM_WORLD)
void	recvData ()
void	release ()
void	sendData ()
void	sendRecvData (bool way=true)
void	setDefaultValue (double val)
void	setWorkSharingAlgo (int method)
void	synchronize ()
virtual	~OverlapDEC ()
Public Member Functions inherited from MEDCoupling::DEC
void	copyFrom (const DEC &other)
	DEC ()
virtual	~DEC ()
Public Member Functions inherited from MEDCoupling::DECOptions
	DECOptions ()
	DECOptions (const DECOptions &deco)
AllToAllMethod	getAllToAllMethod () const
bool	getAsynchronous () const
bool	getForcedRenormalization () const
const std::string &	getMethod () const
TimeInterpolationMethod	getTimeInterpolationMethod () const
void	setAllToAllMethod (AllToAllMethod sp)
void	setAsynchronous (bool dr)
void	setForcedRenormalization (bool dr)
void	setMethod (const char *m)
void	setTimeInterpolationMethod (TimeInterpolationMethod it)
Public Member Functions inherited from INTERP_KERNEL::InterpolationOptions
void	copyOptions (const InterpolationOptions &other)
std::string	filterInterpolationMethod (const std::string &meth) const
double	getBoundingBoxAdjustment () const
double	getBoundingBoxAdjustmentAbs () const
bool	getDoRotate () const
IntersectionType	getIntersectionType () const
std::string	getIntersectionTypeRepr () const
double	getMaxDistance3DSurfIntersect () const
bool	getMeasureAbsStatus () const
double	getMedianPlane () const
double	getMinDotBtwPlane3DSurfIntersect () const
int	getOrientation () const
double	getPrecision () const
int	getPrintLevel () const
SplittingPolicy	getSplittingPolicy () const
std::string	getSplittingPolicyRepr () const
void	init ()
	InterpolationOptions ()
std::string	printOptions () const
void	setBoundingBoxAdjustment (double bba)
void	setBoundingBoxAdjustmentAbs (double bba)
void	setDoRotate (bool dr)
bool	setInterpolationOptions (int print_level, std::string intersection_type, double precision, double median_plane, bool do_rotate, double bounding_box_adjustment, double bounding_box_adjustment_abs, double max_distance_for_3Dsurf_intersect, int orientation, bool measure_abs, std::string splitting_policy)
void	setIntersectionType (IntersectionType it)
void	setMaxDistance3DSurfIntersect (double bba)
void	setMeasureAbsStatus (bool newStatus)
void	setMedianPlane (double mp)
void	setMinDotBtwPlane3DSurfIntersect (double v)
bool	setOptionDouble (const std::string &key, double value)
bool	setOptionInt (const std::string &key, int value)
bool	setOptionString (const std::string &key, const std::string &value)
void	setOrientation (int o)
void	setPrecision (double p)
void	setPrintLevel (int pl)
void	setSplittingPolicy (SplittingPolicy sp)

Additional Inherited Members
Static Public Member Functions inherited from INTERP_KERNEL::InterpolationOptions
static void	CheckAndSplitInterpolationMethod (const std::string &method, std::string &srcMeth, std::string &trgMeth)
Static Public Attributes inherited from INTERP_KERNEL::InterpolationOptions
static const char	BARYCENTRIC_INTERSECT_STR [] ="Barycentric"
static const char	BARYCENTRICGEO2D_INTERSECT_STR [] ="BarycentricGeo2D"
static const char	BOUNDING_BOX_ADJ_ABS_STR [] ="BoundingBoxAdjustmentAbs"
static const char	BOUNDING_BOX_ADJ_STR [] ="BoundingBoxAdjustment"
static const char	CONVEX_INTERSECT2D_STR [] ="Convex"
static const char	DO_ROTATE_STR [] ="DoRotate"
static const char	GENERAL_SPLIT_24_STR [] ="GENERAL_24"
static const char	GENERAL_SPLIT_48_STR [] ="GENERAL_48"
static const char	GEOMETRIC_INTERSECT2D_STR [] ="Geometric2D"
static const char	INTERSEC_TYPE_STR [] ="IntersectionType"
static const char	MAX_DISTANCE_3DSURF_INSECT_STR [] ="MaxDistance3DSurfIntersect"
static const char	MEASURE_ABS_STR [] ="MeasureAbs"
static const char	MEDIANE_PLANE_STR [] ="MedianPlane"
static const char	MIN_DOT_BTW_3DSURF_INSECT_STR [] ="MinDotBetween3DSurfIntersect"
static const char	ORIENTATION_STR [] ="Orientation"
static const char	PLANAR_SPLIT_FACE_5_STR [] ="PLANAR_FACE_5"
static const char	PLANAR_SPLIT_FACE_6_STR [] ="PLANAR_FACE_6"
static const char	POINTLOCATOR_INTERSECT_STR [] ="PointLocator"
static const char	PRECISION_STR [] ="Precision"
static const char	PRINT_LEV_STR [] ="PrintLevel"
static const char	SPLITTING_POLICY_STR [] ="SplittingPolicy"
static const char	TRIANGULATION_INTERSECT2D_STR [] ="Triangulation"
Protected Attributes inherited from MEDCoupling::DEC
const CommInterface *	_comm_interface
Protected Attributes inherited from MEDCoupling::DECOptions
AllToAllMethod	_allToAllMethod
bool	_asynchronous
bool	_forcedRenormalization
std::string	_method
TimeInterpolationMethod	_timeInterpolationMethod

Detailed Description

Overview

The OverlapDEC enables the conservative remapping of fields between two parallel codes. This remapping is based on the computation of intersection volumes on a single processor group. On this processor group are defined two field-templates called A and B. The computation is possible for 3D meshes, 2D meshes, 3D-surface meshes, 1D meshes and 2D-curve meshes. Dimensions must be similar for the distribution templates A and B.

The main difference with InterpKernelDEC is that this DEC works with a single processor group, in which processors will share the work. Consequently each processor manages two field templates (A and B) called source and target. Furthermore all processors in the processor group cooperate in the global interpolation matrix computation. In this respect InterpKernelDEC is a specialization of OverlapDEC.

Algorithm description

Let's consider the following use case that is ran in ParaMEDMEMTest_OverlapDEC.cxx to describes the different steps of the computation. The processor group contains 3 processors.

Example split of the source and target mesh among the 3 procs

Step 1 : Bounding box exchange and global interaction between procs computation.

In order to reduce as much as possible the amount of communications between distant processors, every processor computes a bounding box for A and B. Then a AllToAll communication is performed so that every processor can compute the global interactions between processor. This computation leads every processor to compute the same global TODO list expressed as a list of pair. A pair ( x, y ) means that proc x fieldtemplate A can interact with fieltemplate B of proc y because the two bounding boxes interact. In the example above this computation leads to the following a global TODO list :

(0,0),(0,1),(1,0),(1,2),(2,0),(2,1),(2,2)

Here the pair (0,2) does not appear because the bounding box of fieldtemplateA of proc#2 does not intersect that of fieldtemplate B on proc#0.

Stage performed by MEDCoupling::OverlapElementLocator::computeBoundingBoxes.

Step 2 : Computation of local TODO list

Starting from the global interaction previously computed in Step 1, each proc computes the TODO list per proc. The following rules is chosen : a pair (x,y) can be treated by either proc #x or proc #y, in order to reduce the amount of data transfers among processors. The algorithm chosen for load balancing is the following : Each processor has an empty local TODO list at the beginning. Then for each pair (k,m) in global TODO list, if proc#k has less temporary local list than proc#m pair, (k,m) is added to temporary local TODO list of proc#k. If proc#m has less temporary local TODO list than proc#k pair, (k,m) is added to temporary local TODO list of proc#m. If proc#k and proc#m have the same amount of temporary local TODO list pair, (k,m) is added to temporary local TODO list of proc#k.

In the example above this computation leads to the following local TODO list :

• proc#0 : (0,0)
• proc#1 : (0,1),(1,0)
• proc#2 : (1,2),(2,0),(2,1),(2,2)

The algorithm described here is not perfect for this use case, we hope to enhance it soon.

At this stage each proc knows precisely its local TODO list (with regard to interpolation). The local TODO list of other procs than local is kept for future computations.

Step 3 : Matrix echange between procs

Knowing the local TODO list, the aim now is to exchange field-templates between procs. Each proc computes knowing TODO list per proc computed in Step 2 the exchange TODO list :

In the example above the exchange TODO list gives the following results :

Sending TODO list per proc :

• proc #0 : Send fieldtemplate A to Proc#1, Send fieldtemplate B to Proc#1, Send fieldtemplate B to Proc#2
• Proc #1 : Send fieldtemplate A to Proc#2, Send fieldtemplate B to Proc#2
• Proc #2 : No send.

Receiving TODO list per proc :

• proc #0 : No receiving
• proc #1 : receiving fieldtemplate A from Proc#0, receiving fieldtemplate B from Proc#0
• proc #2 : receiving fieldtemplate B from Proc#0, receiving fieldtemplate A from Proc#1, receiving fieldtemplate B from Proc#1

To avoid as much as possible large volumes of transfers between procs, only relevant parts of meshes are sent. In order for proc#k to send fieldtemplate A to fieldtemplate B of proc #m., proc#k computes the part of mesh A contained in the boundingbox B of proc#m. It implies that the corresponding cellIds or nodeIds of the corresponding part are sent to proc #m too.

Let's consider the couple (k,m) in the TODO list. This couple is treated by either k or m as seen in here in Step2.

As will be dealt in Step 6, for final matrix-vector computations, the resulting matrix of the couple (k,m) wherever it is computed (proc #k or proc #m) will be stored in proc#m.

• If proc #k is in charge (performs the matrix computation) for this couple (k,m), target ids (cells or nodes) of the mesh in proc #m are renumbered, because proc #m has seelected a sub mesh of the target mesh to avoid large amounts of data to transfer. In this case as proc #m is ultimately in charge of the matrix, proc #k must keep preciously the source ids needed to be sent to proc#m. No problem will appear for matrix assembling in proc m for source ids because no restriction was done. Concerning source ids to be sent for the matrix-vector computation, proc k will know precisely which source ids field values to send to proc #m. This is embodied by OverlapMapping::keepTracksOfTargetIds in proc m.
• If proc #m is in charge (performs matrix computation) for this couple (k,m), source ids (cells or nodes) of the mesh in proc #k are renumbered, because proc #k has selected a sub mesh of the source mesh to avoid large amounts of data to transfer. In this case as proc #k is ultimately in charge of the matrix, proc #m receives the source ids from remote proc #k, and thus the matrix is directly correct, no need for renumbering as in Step 5. However proc #k must keep track of the ids sent to proc #m for the matrix-vector computation. This is incarnated by OverlapMapping::keepTracksOfSourceIds in proc k.

This step is performed in MEDCoupling::OverlapElementLocator::exchangeMeshes method.

Step 4 : Computation of the interpolation matrix

After mesh exchange in Step3 each processor has all the required information to treat its local TODO list computed in Step2. This step is potentially CPU costly, which is why the local TODO list per proc is expected to be as well balanced as possible.

The interpolation is performed as the remapper does.

This operation is performed by OverlapInterpolationMatrix::addContribution method.

Step 5 : Global matrix construction.

After having performed the TODO list at the end of Step4 we need to assemble the final matrix.

The final aim is to have a distributed matrix on each proc#k. In order to reduce data exchange during the matrix product process, is built using sizeof(Proc group) std::vector< std::map<int,double> >.

For a proc#k, it is necessary to fetch info of all matrices built in Step4 where the first element in pair (i,j) is equal to k.

After this step, the matrix repartition is the following after a call to MEDCoupling::OverlapMapping::prepare :

• proc#0 : (0,0),(1,0),(2,0)
• proc#1 : (0,1),(2,1)
• proc#2 : (1,2),(2,2)

Tuple (2,1) computed on proc 2 is stored in proc 1 after execution of the function "prepare". This is an example of item 0 in Step2. Tuple (0,1) computed on proc 1 is stored in proc 1 too. This is an example of item 1 in Step2.

In the end MEDCoupling::OverlapMapping::_proc_ids_to_send_vector_st will contain :

• Proc#0 : 0,1
• Proc#1 : 0,2
• Proc#2 : 0,1,2

In the end MEDCoupling::OverlapMapping::_proc_ids_to_recv_vector_st will contain :

• Proc#0 : 0,1,2
• Proc#1 : 0,2
• Proc#2 : 1,2

The method in charge to perform this is : MEDCoupling::OverlapMapping::prepare.

Constructor & Destructor Documentation

OverlapDEC()

MEDCoupling::OverlapDEC::OverlapDEC	(	const std::set< int > &	procIds,
		const MPI_Comm &	world_comm = MPI_COMM_WORLD
	)

References MEDCoupling::CommInterface::commCreate(), MEDCoupling::CommInterface::commGroup(), MEDCoupling::CommInterface::groupFree(), and MEDCoupling::CommInterface::groupIncl().

~OverlapDEC()

MEDCoupling::OverlapDEC::~OverlapDEC ( )

virtual

References release().

Member Function Documentation

release()

void MEDCoupling::OverlapDEC::release

(

)

Destructor involves MPI operations: make sure this is accessible from a proper method for Python wrapping.

References MEDCoupling::CommInterface::commFree().

Referenced by ~OverlapDEC().

sendRecvData()

void MEDCoupling::OverlapDEC::sendRecvData ( bool  way = true )

virtual

Implements MEDCoupling::DEC.

References recvData(), and sendData().

sendData()

void MEDCoupling::OverlapDEC::sendData

(

)

Referenced by sendRecvData().

recvData()

void MEDCoupling::OverlapDEC::recvData

(

)

Referenced by sendRecvData().

synchronize()

void MEDCoupling::OverlapDEC::synchronize ( )

virtual

Implements MEDCoupling::DEC.

References INTERP_KERNEL::InterpolationOptions::getBoundingBoxAdjustmentAbs(), MEDCoupling::ParaFIELD::getField(), MEDCoupling::MEDCouplingFieldDouble::getNumberOfComponents(), and isInGroup().

attachSourceLocalField() [1/3]

void MEDCoupling::OverlapDEC::attachSourceLocalField	(	ParaFIELD *	field,
		bool	ownPt = false
	)

References isInGroup().

Referenced by attachSourceLocalField().

attachTargetLocalField() [1/3]

void MEDCoupling::OverlapDEC::attachTargetLocalField	(	ParaFIELD *	field,
		bool	ownPt = false
	)

References isInGroup().

Referenced by attachTargetLocalField().

attachSourceLocalField() [2/3]

void MEDCoupling::OverlapDEC::attachSourceLocalField

(

MEDCouplingFieldDouble *

field

)

References attachSourceLocalField(), MEDCoupling::MEDCouplingField::getMesh(), MEDCoupling::MEDCouplingMesh::getName(), isInGroup(), and MEDCoupling::ParaFIELD::setOwnSupport().

attachTargetLocalField() [2/3]

void MEDCoupling::OverlapDEC::attachTargetLocalField

(

MEDCouplingFieldDouble *

field

)

References attachTargetLocalField(), MEDCoupling::MEDCouplingField::getMesh(), MEDCoupling::MEDCouplingMesh::getName(), isInGroup(), and MEDCoupling::ParaFIELD::setOwnSupport().

attachSourceLocalField() [3/3]

void MEDCoupling::OverlapDEC::attachSourceLocalField

(

ICoCo::MEDDoubleField *

field

)

References attachSourceLocalField(), and ICoCo::MEDDoubleField::getMCField().

attachTargetLocalField() [3/3]

void MEDCoupling::OverlapDEC::attachTargetLocalField

(

ICoCo::MEDDoubleField *

field

)

References attachTargetLocalField(), and ICoCo::MEDDoubleField::getMCField().

getGroup()

ProcessorGroup* MEDCoupling::OverlapDEC::getGroup

(

)

isInGroup()

bool MEDCoupling::OverlapDEC::isInGroup

(

)

const

References MEDCoupling::ProcessorGroup::containsMyRank().

Referenced by attachSourceLocalField(), attachTargetLocalField(), and synchronize().

setDefaultValue()

void MEDCoupling::OverlapDEC::setDefaultValue

(

double

val

)

setWorkSharingAlgo()

void MEDCoupling::OverlapDEC::setWorkSharingAlgo

(

int

method

)

0 means initial algo from Antho, 1 or 2 means Adrien's algo (2 should be better). Make your choice :-))

debugPrintWorkSharing()

void MEDCoupling::OverlapDEC::debugPrintWorkSharing

(

std::ostream &

ostr

)

const