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MueLu: Fixing Issue #13377 and #13378
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Issues listed above have been addressed.
Threshold has been redefined to 1/threshold.
Unit tests have been modified to be more thorough.

Signed-off-by: Ian Halim <[email protected]>
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Ian Halim committed Oct 17, 2024
1 parent 4dff65a commit 1317d90
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Showing 2 changed files with 185 additions and 51 deletions.
60 changes: 34 additions & 26 deletions packages/muelu/src/Graph/MatrixTransformation/MueLu_CoalesceDropFactory_def.hpp
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Original file line number Diff line number Diff line change
Expand Up @@ -591,13 +591,27 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level

//move from host to device
auto ghostedDiagValsView = Kokkos::subview(ghostedDiag->getDeviceLocalView(Xpetra::Access::ReadOnly), Kokkos::ALL(), 0);
auto boundaryNodesDevice = Kokkos::create_mirror_view_and_copy(ExecSpace(), boundaryNodes);
auto thresholdKokkos = static_cast<impl_scalar_type>(threshold);
auto realThresholdKokkos = implATS::magnitude(thresholdKokkos);
auto columnsDevice = Kokkos::create_mirror_view(ExecSpace(), columns);

auto At = Utilities::Op2TpetraCrs(A);
auto A_device = At->getLocalMatrixDevice();
auto A_device = A->getLocalMatrixDevice();
RCP<LWGraph> graph = rcp(new LWGraph(A->getCrsGraph(), "graph of A"));
RCP<const Import> importer = A->getCrsGraph()->getImporter();
RCP<LocalOrdinalVector> boundaryNodesVector = Xpetra::VectorFactory<LO, LO, GO, NO>::Build(graph->GetDomainMap());
RCP<LocalOrdinalVector> boundaryColumnVector;
for(size_t i = 0; i < graph->GetNodeNumVertices(); i++) {
boundaryNodesVector->getDataNonConst(0)[i] = boundaryNodes[i];
}
if(!importer.is_null()) {
boundaryColumnVector = Xpetra::VectorFactory<LO, LO, GO, NO>::Build(graph->GetImportMap());
boundaryColumnVector->doImport(*boundaryNodesVector, *importer, Xpetra::INSERT);
}
else {
boundaryColumnVector = boundaryNodesVector;
}
auto boundaryColumn = boundaryColumnVector->getDeviceLocalView(Xpetra::Access::ReadOnly);
auto boundary = Kokkos::subview(boundaryColumn, Kokkos::ALL(), 0);

Kokkos::View<LO*, ExecSpace>rownnzView("rownnzView", A_device.numRows());
auto drop_views = Kokkos::View<bool*, ExecSpace>("drop_views", A_device.nnz());
Expand All @@ -608,30 +622,24 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level
auto rowView = A_device.rowConst(row);
size_t nnz = rowView.length;

size_t dropSize = 0;
auto drop_view = Kokkos::subview(drop_views, Kokkos::make_pair(A_device.graph.row_map(row), A_device.graph.row_map(row+1)));
auto index_view = Kokkos::subview(index_views, Kokkos::make_pair(A_device.graph.row_map(row), A_device.graph.row_map(row+1)));

//find magnitudes
Kokkos::parallel_reduce(Kokkos::TeamThreadRange(teamMember, (LO)nnz), [&](const LO colID, size_t &count) {
Kokkos::parallel_for(Kokkos::TeamThreadRange(teamMember, (LO)nnz), [&](const LO colID) {
index_view(colID) = colID;
LO col = rowView.colidx(colID);
//ignore diagonals for now, they are checked again later
if(row == col) {
drop_view(colID) = true;
count++;
}
//Don't aggregate boundaries
else if(boundaryNodesDevice(colID)) {
if(row == col || boundary(col)) {
drop_view(colID) = true;
}
else {
drop_view(colID) = false;
count++;
}
}, dropSize);
});

size_t dropStart = dropSize;
size_t dropStart = nnz;
if (classicalAlgo == unscaled_cut) {
//push diagonals and boundaries to the right, sort everything else by aij on the left
Kokkos::Experimental::sort_team(teamMember, index_view, [=](size_t& x, size_t& y) -> bool {
Expand All @@ -646,7 +654,7 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level
});

//find index where dropping starts
Kokkos::parallel_reduce(Kokkos::TeamThreadRange(teamMember, 1, dropSize), [=](size_t i, size_t& min) {
Kokkos::parallel_reduce(Kokkos::TeamThreadRange(teamMember, 1, nnz), [=](size_t i, size_t& min) {
auto const& x = index_view(i - 1);
auto const& y = index_view(i);
typename implATS::magnitudeType x_aij = 0;
Expand All @@ -658,7 +666,7 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level
y_aij = implATS::magnitude(rowView.value(y) * rowView.value(y));
}

if(x_aij > realThresholdKokkos * y_aij) {
if(realThresholdKokkos * realThresholdKokkos * x_aij > y_aij) {
if(i < min) {
min = i;
}
Expand All @@ -673,30 +681,30 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level
else {
auto x_aij = implATS::magnitude(rowView.value(x) * rowView.value(x));
auto y_aij = implATS::magnitude(rowView.value(y) * rowView.value(y));
auto x_aiiajj = implATS::magnitude(thresholdKokkos * thresholdKokkos * ghostedDiagValsView(rowView.colidx(x)) * ghostedDiagValsView(row));
auto y_aiiajj = implATS::magnitude(thresholdKokkos * thresholdKokkos * ghostedDiagValsView(rowView.colidx(y)) * ghostedDiagValsView(row));
auto x_aiiajj = implATS::magnitude(ghostedDiagValsView(rowView.colidx(x)) * ghostedDiagValsView(row));
auto y_aiiajj = implATS::magnitude(ghostedDiagValsView(rowView.colidx(y)) * ghostedDiagValsView(row));
return (x_aij / x_aiiajj) > (y_aij / y_aiiajj);
}
});

//find index where dropping starts
Kokkos::parallel_reduce(Kokkos::TeamThreadRange(teamMember, 1, dropSize), [=](size_t i, size_t& min) {
Kokkos::parallel_reduce(Kokkos::TeamThreadRange(teamMember, 1, nnz), [=](size_t i, size_t& min) {
auto const& x = index_view(i - 1);
auto const& y = index_view(i);
typename implATS::magnitudeType x_val = 0;
typename implATS::magnitudeType y_val = 0;
if(!drop_view(x)) {
typename implATS::magnitudeType x_aij = implATS::magnitude(rowView.value(x) * rowView.value(x));
typename implATS::magnitudeType x_aiiajj = implATS::magnitude(thresholdKokkos * thresholdKokkos * ghostedDiagValsView(rowView.colidx(x)) * ghostedDiagValsView(row));
typename implATS::magnitudeType x_aiiajj = implATS::magnitude(ghostedDiagValsView(rowView.colidx(x)) * ghostedDiagValsView(row));
x_val = x_aij / x_aiiajj;
}
if(!drop_view(y)) {
typename implATS::magnitudeType y_aij = implATS::magnitude(rowView.value(y) * rowView.value(y));
typename implATS::magnitudeType y_aiiajj = implATS::magnitude(thresholdKokkos * thresholdKokkos * ghostedDiagValsView(rowView.colidx(y)) * ghostedDiagValsView(row));
typename implATS::magnitudeType y_aiiajj = implATS::magnitude(ghostedDiagValsView(rowView.colidx(y)) * ghostedDiagValsView(row));
y_val = y_aij / y_aiiajj;
}

if(x_val > realThresholdKokkos * y_val) {
if(realThresholdKokkos * realThresholdKokkos * x_val > y_val) {
if(i < min) {
min = i;
}
Expand All @@ -705,15 +713,15 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level
}

//drop everything to the right of where values stop passing threshold
if(dropStart < dropSize) {
Kokkos::parallel_for(Kokkos::TeamThreadRange(teamMember, dropStart, dropSize), [=](size_t i) {
if(dropStart < nnz) {
Kokkos::parallel_for(Kokkos::TeamThreadRange(teamMember, dropStart, nnz), [=](size_t i) {
drop_view(index_view(i)) = true;
});
}

LO rownnz = 0;
GO rowDropped = 0;
Kokkos::parallel_reduce(Kokkos::TeamThreadRange(teamMember, dropSize), [=](const size_t idxID, LO& keep, GO& drop) {
Kokkos::parallel_reduce(Kokkos::TeamThreadRange(teamMember, nnz), [=](const size_t idxID, LO& keep, GO& drop) {
LO col = rowView.colidx(idxID);
//don't drop diagonal
if(row == col || !drop_view(idxID)) {
Expand Down Expand Up @@ -1381,7 +1389,7 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level
auto const& y = drop_vec[i];
auto a = x.val;
auto b = y.val;
if (a > realThreshold * b) {
if (realThreshold * realThreshold * a > b) {
drop = true;
#ifdef HAVE_MUELU_DEBUG
if (distanceLaplacianCutVerbose) {
Expand All @@ -1404,7 +1412,7 @@ void CoalesceDropFactory<Scalar, LocalOrdinal, GlobalOrdinal, Node>::Build(Level
auto const& y = drop_vec[i];
auto a = x.val / x.diag;
auto b = y.val / y.diag;
if (a > realThreshold * b) {
if (realThreshold * realThreshold * a > b) {
drop = true;
#ifdef HAVE_MUELU_DEBUG
if (distanceLaplacianCutVerbose) {
Expand Down
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