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Grid/Grid/algorithms/deflation/MultiRHSDeflation.h
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/*************************************************************************************
Grid physics library, www.github.com/paboyle/Grid
Source file: MultiRHSDeflation.h
Copyright (C) 2023
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.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License along
with this program; if not, write to the Free Software Foundation, Inc.,
51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
See the full license in the file "LICENSE" in the top level distribution directory
*************************************************************************************/
/* END LEGAL */
#pragma once
NAMESPACE_BEGIN(Grid);
/* Need helper object for BLAS accelerated mrhs projection
i) MultiRHS Deflation
Import Evecs -> nev x vol x internal
Import vector of Lattice objects -> nrhs x vol x internal
=> Cij (nrhs x Nev) via GEMM.
=> Guess (nrhs x vol x internal) = C x evecs (via GEMM)
Export
ii) MultiRHS block projection
Import basis -> nblock x nbasis x (block x internal)
Import vector of fine lattice objects -> nblock x nrhs x (block x internal)
=> coarse_(nrhs x nbasis )^block = via batched GEMM
iii) Alternate interface:
Import higher dim Lattice object-> vol x nrhs layout
*/
template<class Field>
class MultiRHSDeflation
{
public:
typedef typename Field::scalar_type scalar;
typedef typename Field::scalar_object scalar_object;
typedef typename Field::vector_object vobj;
int nev;
std::vector<RealD> eval;
GridBase *grid;
uint64_t vol;
uint64_t words;
deviceVector<scalar> BLAS_E; // nev x vol -- the eigenbasis (up to a 1/sqrt(lambda))
deviceVector<scalar> BLAS_R; // nrhs x vol -- the sources
deviceVector<scalar> BLAS_G; // nrhs x vol -- the guess
deviceVector<scalar> BLAS_C; // nrhs x nev -- the coefficients
MultiRHSDeflation(){};
~MultiRHSDeflation(){ Deallocate(); };
void Deallocate(void)
{
nev=0;
grid=nullptr;
vol=0;
words=0;
// deviceVector is a std::vector with a device allocator: resize(0) drops
// the size and keeps the capacity, returning no device memory. Swapping
// with an empty vector destroys the buffer.
deviceVector<scalar>().swap(BLAS_E);
deviceVector<scalar>().swap(BLAS_R);
deviceVector<scalar>().swap(BLAS_C);
deviceVector<scalar>().swap(BLAS_G);
}
// Resident (non-evictable) device memory held by this deflator.
uint64_t DeviceBytes(void)
{
return (BLAS_E.capacity()+BLAS_R.capacity()+BLAS_C.capacity()+BLAS_G.capacity())*sizeof(scalar);
}
void Allocate(int _nev,GridBase *_grid)
{
nev=_nev;
grid=_grid;
vol = grid->lSites();
words = sizeof(scalar_object)/sizeof(scalar);
eval.resize(nev);
BLAS_E.resize (vol * words * nev );
std::cout << GridLogMessage << " Allocate for "<<nev<<" eigenvectors and volume "<<vol<<std::endl;
}
void ImportEigenVector(Field &evec,RealD &_eval, int ev)
{
// std::cout << " ev " <<ev<<" eval "<<_eval<< std::endl;
GRID_ASSERT(ev<eval.size());
eval[ev] = _eval;
int64_t offset = ev*vol*words;
autoView(v,evec,AcceleratorRead);
acceleratorCopyDeviceToDevice(&v[0],&BLAS_E[offset],sizeof(scalar_object)*vol);
}
void ImportEigenBasis(std::vector<Field> &evec,std::vector<RealD> &_eval)
{
ImportEigenBasis(evec,_eval,0,evec.size());
}
// Could use to import a batch of eigenvectors
void ImportEigenBasis(std::vector<Field> &evec,std::vector<RealD> &_eval, int _ev0, int _nev)
{
GRID_ASSERT(_ev0+_nev<=evec.size());
Allocate(_nev,evec[0].Grid());
// Imports a sub-batch of eigenvectors, _ev0, ..., _ev0+_nev-1
for(int e=0;e<nev;e++){
std::cout << "Importing eigenvector "<<e<<" evalue "<<_eval[_ev0+e]<<std::endl;
ImportEigenVector(evec[_ev0+e],_eval[_ev0+e],e);
}
}
/////////////////////////////////////////////////////////////////////////
// Sources as a vector of D-dimensional fields: each is one contiguous
// column of BLAS_R already, so import/export are straight copies.
// The eigenvectors may live on a D grid or on the Nrhs=1 D+1 grid of the
// same local volume; the two are the same bytes, so only the site count
// is checked, not grid identity.
/////////////////////////////////////////////////////////////////////////
void DeflateSources(std::vector<Field> &source,std::vector<Field> & guess)
{
int nrhs = source.size();
GRID_ASSERT(source.size()==guess.size());
GRID_ASSERT(grid->lSites() == guess[0].Grid()->lSites());
conformable(guess[0],source[0]);
int64_t vw = vol * words;
BLAS_R.resize(nrhs * vw); // cost free if size doesn't change
BLAS_G.resize(nrhs * vw); // cost free if size doesn't change
BLAS_C.resize(nev * nrhs);// cost free if size doesn't change
for(int r=0;r<nrhs;r++){
int64_t offset = r*vw;
autoView(v,source[r],AcceleratorRead);
acceleratorCopyDeviceToDevice(&v[0],&BLAS_R[offset],sizeof(scalar_object)*vol);
}
DeflateBLAS(nrhs);
for(int r=0;r<nrhs;r++){
int64_t offset = r*vw;
autoView(v,guess[r],AcceleratorWrite);
acceleratorCopyDeviceToDevice(&BLAS_G[offset],&v[0],sizeof(scalar_object)*vol);
}
}
/////////////////////////////////////////////////////////////////////////
// Sources as ONE D+1 dimensional multiRHS field, rhs innermost
// (dimension 0, undistributed) on an UNVECTORISED coarse space, so the
// site index is rhs + nrhs*x with x the D-dimensional site. The GEMM
// wants x contiguous per rhs, so the import is a permutation, one fused
// pass over the field; likewise the export. No slices.
/////////////////////////////////////////////////////////////////////////
void DeflateSources(const Field &source_mrhs, Field &guess_mrhs)
{
conformable(source_mrhs,guess_mrhs);
GridBase *hi = source_mrhs.Grid();
GRID_ASSERT(hi->_ndimension == grid->_ndimension+1);
GRID_ASSERT(hi->_processors[0] == 1);
GRID_ASSERT(hi->_simd_layout[0]== 1);
GRID_ASSERT(vobj::Nsimd() == 1);
int nrhs = hi->_fdimensions[0];
GRID_ASSERT(hi->lSites() == nrhs*vol);
int64_t vw = vol * words;
BLAS_R.resize(nrhs * vw);
BLAS_G.resize(nrhs * vw);
BLAS_C.resize(nev * nrhs);
ImportSourcesMrhs(source_mrhs,nrhs);
DeflateBLAS(nrhs);
ExportGuessMrhs(guess_mrhs,nrhs);
}
void ImportSourcesMrhs(const Field &source_mrhs,int nrhs)
{
const int64_t lwords = words, lnrhs = nrhs, vw = vol*words;
autoView(v,source_mrhs,AcceleratorRead);
auto vp = &v[0];
scalar *R = &BLAS_R[0];
accelerator_for(scr, lnrhs*vol, 1, {
int64_t r = scr % lnrhs;
int64_t x = scr / lnrhs;
const scalar *s = (const scalar *)&vp[scr];
for(int64_t w=0;w<lwords;w++) R[r*vw + x*lwords + w] = s[w];
});
}
void ExportGuessMrhs(Field &guess_mrhs,int nrhs)
{
const int64_t lwords = words, lnrhs = nrhs, vw = vol*words;
autoView(v,guess_mrhs,AcceleratorWrite);
auto vp = &v[0];
scalar *G = &BLAS_G[0];
accelerator_for(scr, lnrhs*vol, 1, {
int64_t r = scr % lnrhs;
int64_t x = scr / lnrhs;
scalar *g = (scalar *)&vp[scr];
for(int64_t w=0;w<lwords;w++) g[w] = G[r*vw + x*lwords + w];
});
}
/////////////////////////////////////////////////////////////////////////
// BLAS_R (nrhs columns of vol*words) -> BLAS_G, through the imported
// eigenbasis: C = E^dag R / lambda, G = E C.
/////////////////////////////////////////////////////////////////////////
void DeflateBLAS(int nrhs)
{
int64_t vw = vol * words;
RealD t0 = usecond();
/*
* in Fortran column major notation (cuBlas order)
*
* Exe = [e1(x)][..][en(x)]
*
* Rxr = [r1(x)][..][rm(x)]
*
* C_er = E^dag R
* C_er = C_er / lambda_e
* G_xr = Exe Cer
*/
deviceVector<scalar *> Ed(1);
deviceVector<scalar *> Rd(1);
deviceVector<scalar *> Cd(1);
deviceVector<scalar *> Gd(1);
scalar * Eh = & BLAS_E[0];
scalar * Rh = & BLAS_R[0];
scalar * Ch = & BLAS_C[0];
scalar * Gh = & BLAS_G[0];
acceleratorPut(Ed[0],Eh);
acceleratorPut(Rd[0],Rh);
acceleratorPut(Cd[0],Ch);
acceleratorPut(Gd[0],Gh);
GridBLAS BLAS;
/////////////////////////////////////////
// C_er = E^dag R
/////////////////////////////////////////
BLAS.gemmBatched(GridBLAS_OP_C,GridBLAS_OP_N,
nev,nrhs,vw,
scalar(1.0),
Ed,
Rd,
scalar(0.0), // wipe out C
Cd);
BLAS.synchronise();
GRID_ASSERT(BLAS_C.size()==nev*nrhs);
std::vector<scalar> HOST_C(BLAS_C.size()); // nrhs . nev -- the coefficients
acceleratorCopyFromDevice(&BLAS_C[0],&HOST_C[0],BLAS_C.size()*sizeof(scalar));
grid->GlobalSumVector(&HOST_C[0],nev*nrhs);
for(int e=0;e<nev;e++){
scalar lam(1.0/eval[e]); // in the coarse scalar: fp32 coarse spaces too
for(int r=0;r<nrhs;r++){
int off = e+nev*r;
HOST_C[off]=HOST_C[off] * lam;
// std::cout << "C["<<e<<"]["<<r<<"] ="<<HOST_C[off]<< " eval[e] "<<eval[e] <<std::endl;
}
}
acceleratorCopyToDevice(&HOST_C[0],&BLAS_C[0],BLAS_C.size()*sizeof(scalar));
/////////////////////////////////////////
// Guess G_xr = Exe Cer
/////////////////////////////////////////
BLAS.gemmBatched(GridBLAS_OP_N,GridBLAS_OP_N,
vw,nrhs,nev,
scalar(1.0),
Ed, // x . nev
Cd, // nev . nrhs
scalar(0.0),
Gd);
BLAS.synchronise();
RealD t1 = usecond();
std::cout << GridLogMessage << "MultiRHSDeflation for "<<nrhs<<" sources with "<<nev<<" eigenvectors took " << (t1-t0)/1e3 <<" ms"<<std::endl;
}
};
NAMESPACE_END(Grid);