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Grid/tests/debug/Test_schur2d_redist.cc
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/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: ./tests/debug/Test_schur2d_redist.cc
Copyright (C) 2026
Author: Peter Boyle <pboyle@bnl.gov>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
See the full license in the file "LICENSE" in the top level distribution
directory
*************************************************************************************/
/* END LEGAL */
//////////////////////////////////////////////////////////////////////////////
// Regression gate for BlockCyclicRedistribute and the full stage-4 path
//
// 1D rank-major rows -> block cyclic -> Invert -> back to 1D rows
//
// which is exactly what DENSE_SCHUR2D runs inside DenseCoarseMatrix.
// CPU build under mpirun at n = 1,2,3,4.
//
// T1 : RowsToCyclic against a direct ImportGlobal of the same matrix --
// BITWISE (pure data movement, no arithmetic).
// T2 : round trip rows -> 2D -> rows -- BITWISE, uniform AND non-uniform
// rowStart, layouts with ragged trailing blocks.
// T3 : full pipeline inverse against a host Gauss-Jordan reference.
// T4 : CROSS-IMPLEMENTATION: the same matrix inverted by the 1D
// RecursiveSchurInverse and by the 2D pipeline; results compared
// element-wise. Two independent implementations, two independent
// decompositions, one answer.
//////////////////////////////////////////////////////////////////////////////
#include <Grid/Grid.h>
#include <Grid/algorithms/multigrid/RecursiveSchurInverse.h>
#include <Grid/algorithms/multigrid/BlockCyclicSchurInverse.h>
#include <Grid/algorithms/multigrid/BlockCyclicRedistribute.h>
using namespace Grid;
static int failures = 0;
static void Report(const std::string &name, bool pass, const std::string &detail="")
{
std::cout << GridLogMessage << " " << name << (pass ? " PASS" : " ** FAIL **");
if ( detail.size() ) std::cout << " " << detail;
std::cout << std::endl;
if ( !pass ) failures++;
}
static ComplexD Fill(int64_t i, int64_t j, int salt)
{
double x = std::sin(0.7*i + 1.3*j + 0.31*salt);
double y = std::cos(1.9*i - 0.4*j + 0.77*salt);
return ComplexD(x,y);
}
static void MakeMatrix(std::vector<ComplexD> &A, int64_t N, int salt)
{
A.resize((uint64_t)N*N);
for(int64_t j=0;j<N;j++)
for(int64_t i=0;i<N;i++)
A[i+j*N] = Fill(i,j,salt) + ((i==j) ? ComplexD(3.0*N,0.5) : ComplexD(0.0,0.0));
}
static void HostInverse(std::vector<ComplexD> A, std::vector<ComplexD> &X, int64_t N)
{
X.assign((uint64_t)N*N, ComplexD(0.0,0.0));
for(int64_t i=0;i<N;i++) X[i+i*N] = ComplexD(1.0,0.0);
for(int64_t c=0;c<N;c++){
int64_t piv=c; double mx = std::abs(A[c+c*N]);
for(int64_t r=c+1;r<N;r++)
if ( std::abs(A[r+c*N]) > mx ){ mx=std::abs(A[r+c*N]); piv=r; }
GRID_ASSERT( mx > 0.0 );
if ( piv != c )
for(int64_t j=0;j<N;j++){ std::swap(A[c+j*N],A[piv+j*N]); std::swap(X[c+j*N],X[piv+j*N]); }
ComplexD d = ComplexD(1.0,0.0)/A[c+c*N];
for(int64_t j=0;j<N;j++){ A[c+j*N]*=d; X[c+j*N]*=d; }
for(int64_t r=0;r<N;r++){
if ( r==c ) continue;
ComplexD f = A[r+c*N];
if ( f == ComplexD(0.0,0.0) ) continue;
for(int64_t j=0;j<N;j++){ A[r+j*N]-=f*A[c+j*N]; X[r+j*N]-=f*X[c+j*N]; }
}
}
}
// Ownership tables over the ranks: uniform-ish, and deliberately lopsided.
static std::vector<int64_t> MakeRowStart(int64_t N, int P, int lopsided)
{
std::vector<int64_t> t(P+1); t[0]=0;
for(int r=0;r<P;r++){
int64_t base = N/P;
int64_t extra = ( r < (int)(N%P) ) ? 1 : 0;
int64_t n = base + extra;
if ( lopsided ){ // shift work toward low ranks
if ( r==0 && P>1 ) n = std::min(N, base+extra+3);
if ( r==P-1 ) n = N - t[r]; // remainder
}
t[r+1] = std::min(N, t[r]+n);
}
t[P]=N;
return t;
}
int main(int argc, char **argv)
{
Grid_init(&argc, &argv);
GridCartesian *grid = SpaceTimeGrid::makeFourDimGrid(GridDefaultLatt(),
GridDefaultSimd(Nd, vComplexD::Nsimd()),
GridDefaultMpi());
const int P = grid->ProcessorCount();
const int me = grid->ThisRank();
std::vector<std::pair<int,int>> grids;
for(int r=1;r<=P;r++) if ( P%r==0 ) grids.push_back({r,P/r});
struct Cfg { int64_t N; int64_t nb; };
std::vector<Cfg> cfgs = { {24,4}, {26,4}, {17,5}, {30,7}, {33,3} };
std::cout << GridLogMessage << "BlockCyclicRedistribute regression: P=" << P << std::endl;
////////////////////////////////////////////////////////////////////////
// T1 + T2 : distribution correctness and round trip, bitwise.
////////////////////////////////////////////////////////////////////////
{
bool ok1 = true, ok2 = true;
for(int lop=0; lop<2; lop++){
for(auto &g : grids){
for(auto &c : cfgs){
int64_t N = c.N;
std::vector<int64_t> rowStart = MakeRowStart(N,P,lop);
int64_t myrows = rowStart[me+1]-rowStart[me];
std::vector<ComplexD> Ag; MakeMatrix(Ag, N, 21);
// my 1D rows, column major ld = myrows
std::vector<ComplexD> h((uint64_t)std::max<int64_t>(myrows,1)*N);
for(int64_t j=0;j<N;j++)
for(int64_t i=0;i<myrows;i++)
h[i + j*myrows] = Ag[(rowStart[me]+i) + j*N];
deviceVector<ComplexD> rows1d(h.size());
acceleratorCopyToDevice(&h[0], &rows1d[0], h.size()*sizeof(ComplexD));
BlockCyclicMatrix A(grid,N,c.nb,g.first,g.second);
BlockCyclicMatrix R(grid,N,c.nb,g.first,g.second);
BlockCyclicRedistribute::RowsToCyclic(grid,rowStart,&rows1d[0],myrows,A);
R.ImportGlobal(Ag);
// T1: bitwise against direct import
{
std::vector<ComplexD> x((uint64_t)A.layout.mloc*A.layout.nloc);
std::vector<ComplexD> y(x.size());
if ( x.size() ){
acceleratorCopyFromDevice(&A.data[0], &x[0], x.size()*sizeof(ComplexD));
acceleratorCopyFromDevice(&R.data[0], &y[0], y.size()*sizeof(ComplexD));
}
for(uint64_t i=0;i<x.size();i++) if ( !(x[i]==y[i]) ) ok1 = false;
}
// T2: round trip, bitwise
{
deviceVector<ComplexD> back(h.size());
std::vector<ComplexD> hb(h.size(), ComplexD(0.0,0.0));
acceleratorCopyToDevice(&hb[0], &back[0], hb.size()*sizeof(ComplexD));
BlockCyclicRedistribute::CyclicToRows(grid,rowStart,A,&back[0],myrows);
acceleratorCopyFromDevice(&back[0], &hb[0], hb.size()*sizeof(ComplexD));
for(int64_t j=0;j<N;j++)
for(int64_t i=0;i<myrows;i++)
if ( !(hb[i+j*myrows]==h[i+j*myrows]) ) ok2 = false;
}
}
}
}
Report("T1 RowsToCyclic == ImportGlobal, bitwise", ok1);
Report("T2 round trip rows->2D->rows, bitwise, incl. lopsided rowStart", ok2);
}
////////////////////////////////////////////////////////////////////////
// T3 + T4 : the DENSE_SCHUR2D pipeline against the host reference and
// against the INDEPENDENT 1D RecursiveSchurInverse.
////////////////////////////////////////////////////////////////////////
{
bool ok3 = true, ok4 = true;
double worst3 = 0.0, worst4 = 0.0;
BlockCyclicSchurInverse RSI2;
for(auto &g : grids){
for(auto &c : cfgs){
int64_t N = c.N;
std::vector<int64_t> rowStart = MakeRowStart(N,P,0);
int64_t myrows = rowStart[me+1]-rowStart[me];
std::vector<ComplexD> Ag, Ref;
MakeMatrix(Ag, N, 22);
HostInverse(Ag, Ref, N);
std::vector<ComplexD> h((uint64_t)std::max<int64_t>(myrows,1)*N);
for(int64_t j=0;j<N;j++)
for(int64_t i=0;i<myrows;i++)
h[i + j*myrows] = Ag[(rowStart[me]+i) + j*N];
double mxref = 0.0;
for(auto &z : Ref) mxref = std::max(mxref, std::abs(z));
// ---- 2D pipeline: rows -> cyclic -> invert -> rows ----
std::vector<ComplexD> h2d(h.size());
{
deviceVector<ComplexD> rows1d(h.size());
acceleratorCopyToDevice(&h[0], &rows1d[0], h.size()*sizeof(ComplexD));
BlockCyclicMatrix A(grid,N,c.nb,g.first,g.second);
BlockCyclicRedistribute::RowsToCyclic(grid,rowStart,&rows1d[0],myrows,A);
RSI2.Invert(A);
BlockCyclicRedistribute::CyclicToRows(grid,rowStart,A,&rows1d[0],myrows);
acceleratorCopyFromDevice(&rows1d[0], &h2d[0], h2d.size()*sizeof(ComplexD));
}
for(int64_t j=0;j<N;j++)
for(int64_t i=0;i<myrows;i++){
double d = std::abs(h2d[i+j*myrows]-Ref[(rowStart[me]+i)+j*N])/mxref;
worst3 = std::max(worst3,d);
if ( d > 1.0e-9 ) ok3 = false;
}
// ---- 1D RecursiveSchurInverse on the same matrix ----
{
BlockRows Ar; Ar.Resize(myrows, N);
acceleratorCopyToDevice(&h[0], &Ar.data[0], h.size()*sizeof(ComplexD));
std::vector<int64_t> rs = rowStart;
RecursiveSchurInverse RSI1(grid, N, rs, 1<<20);
RSI1.Invert(Ar);
std::vector<ComplexD> h1d(h.size());
acceleratorCopyFromDevice(&Ar.data[0], &h1d[0], h1d.size()*sizeof(ComplexD));
for(int64_t j=0;j<N;j++)
for(int64_t i=0;i<myrows;i++){
double d = std::abs(h2d[i+j*myrows]-h1d[i+j*myrows])/mxref;
worst4 = std::max(worst4,d);
if ( d > 1.0e-9 ) ok4 = false;
}
}
}
}
Report("T3 2D pipeline vs host reference", ok3, "worst "+std::to_string(worst3));
Report("T4 2D pipeline vs 1D RecursiveSchurInverse", ok4, "worst "+std::to_string(worst4));
}
{
uint64_t f = failures; grid->GlobalSum(f);
if ( f && !failures )
std::cout << GridLogMessage << " ** failures on OTHER ranks: " << f << " **" << std::endl;
failures = (int)f;
}
std::cout << GridLogMessage << (failures ? "Test_schur2d_redist: FAILURES"
: "Test_schur2d_redist: ALL PASS") << std::endl;
Grid_finalize();
return failures ? 1 : 0;
}