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Changes to dense inverse AND improved timing on comms

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This commit is contained in:
Peter Boyle
2026-08-22 11:43:13 -04:00
parent 152e9ecf3b
commit 1e287b6b30
8 changed files with 274 additions and 52 deletions
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examples/Example_pvdagm_v2_3level_DenseCoarseMatrix.cc
+27 -1
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@@ -90,6 +90,14 @@ RealD OuterTol = 1.0e-8;
int OuterMmax = 8;
int OuterNstep = 8;
// Halo exchange in reduced precision on the fine stencils. Stencil::SloppyComms
// is a plain runtime setter (Stencil.h:303) applied to the full/even/odd stencils
// of an operator that is already built, so this costs no extra storage and no
// second operator. Benchmark_dwf at this decomposition measures ~1.6x on the
// fine Dhop, consistent with the uncompressed halo being ~1.6x the interior
// compute time. Set FineSloppyComms=0 to recover the exact-comms behaviour.
int FineSloppyComms = 1;
void ParseEnvironment(void)
{
if(getenv("MASS")) mass = atof(getenv("MASS"));
@@ -104,6 +112,7 @@ void ParseEnvironment(void)
if(getenv("CoarseSolverOrder")) CoarseSolverOrder = atoi(getenv("CoarseSolverOrder"));
if(getenv("OuterTol")) OuterTol = atof(getenv("OuterTol"));
if(getenv("OuterMmax")) OuterMmax = atoi(getenv("OuterMmax"));
if(getenv("FineSloppyComms")) FineSloppyComms = atoi(getenv("FineSloppyComms"));
if(getenv("OuterNstep")) OuterNstep = atoi(getenv("OuterNstep"));
if(getenv("LATT")){
Coordinate l;
@@ -475,6 +484,16 @@ int main (int argc, char ** argv)
MobiusFermionD Ddwf(Umu,*FGrid,*FrbGrid,*UGrid,*UrbGrid,mass,M5,b,c);
MobiusFermionD Dpv (Umu,*FGrid,*FrbGrid,*UGrid,*UrbGrid,1.0, M5,b,c);
// Reduced-precision halo on both fine operators. PVdagM and ShiftedPVdagM are
// thin wrappers over these same objects, so this covers coarsening, the fine
// smoother, the V-cycle and the outer Krylov alike. The final residual check
// below turns it off again: a verification computed with a sloppy operator
// would certify the wrong matrix.
Ddwf.SloppyComms(FineSloppyComms);
Dpv .SloppyComms(FineSloppyComms);
std::cout << GridLogMessage << "Fine stencils: SloppyComms = " << FineSloppyComms
<< (FineSloppyComms ? " (reduced-precision halo)" : " (exact halo)") << std::endl;
typedef PVdagMLinearOperator<MobiusFermionD,LatticeFermionD> PVdagM_t;
typedef ShiftedPVdagMLinearOperator<MobiusFermionD,LatticeFermionD> ShiftedPVdagM_t;
PVdagM_t PVdagM(Ddwf,Dpv);
@@ -815,13 +834,20 @@ int main (int argc, char ** argv)
std::cout << GridLogMessage << "V2 3-level solve Nrhs "<<nr<<" total " << w.Elapsed()
<< " (per RHS: " << w.useconds()/1.0e6/nr << " s)" << std::endl;
// Verify against the EXACT operator: the solve may have used a reduced
// precision halo, but the residual we report must not.
Ddwf.SloppyComms(0);
Dpv .SloppyComms(0);
{ LatticeFermionD Ax(FGrid); RealD worst=0.0;
for(int r=0;r<nr;r++){ PVdagM.Op(sol[r],Ax); Ax=Ax-src[r];
RealD rn=std::sqrt(norm2(Ax)/norm2(src[r]));
std::cout << GridLogMessage << "FINAL Nrhs "<<nr<<": rhs["<<r<<"] true residual = " << rn << std::endl;
worst=std::max(worst,rn); }
std::cout << GridLogMessage << "FINAL Nrhs "<<nr<<": worst-case residual = " << worst << std::endl;
std::cout << GridLogMessage << "FINAL Nrhs "<<nr<<": worst-case residual = " << worst
<< " (exact-halo verification)" << std::endl;
}
Ddwf.SloppyComms(FineSloppyComms);
Dpv .SloppyComms(FineSloppyComms);
// The operators borrow these grids and build a PaddedCell on them, so
// they must let go before the grids are destroyed.