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Merge pull request #424 from giltirn/feature/dirichlet-precchange

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Precision change implementation
This commit is contained in:
Peter Boyle
2023-03-22 23:04:52 -04:00
committed by GitHub
parent 52384e34cf 83d86943db
commit 23298acb81
9 changed files with 744 additions and 19 deletions
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127
Grid/lattice/Lattice_transfer.h
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@ -1080,6 +1080,7 @@ vectorizeFromRevLexOrdArray( std::vector<sobj> &in, Lattice<vobj> &out)
});
}
//Very fast precision change. Requires in/out objects to reside on same Grid (e.g. by using double2 for the double-precision field)
template<class VobjOut, class VobjIn>
void precisionChangeFast(Lattice<VobjOut> &out, const Lattice<VobjIn> &in)
{
@ -1097,9 +1098,9 @@ void precisionChangeFast(Lattice<VobjOut> &out, const Lattice<VobjIn> &in)
precisionChange(vout,vin,N);
});
}
//Convert a Lattice from one precision to another
//Convert a Lattice from one precision to another (original, slow implementation)
template<class VobjOut, class VobjIn>
void precisionChange(Lattice<VobjOut> &out, const Lattice<VobjIn> &in)
void precisionChangeOrig(Lattice<VobjOut> &out, const Lattice<VobjIn> &in)
{
assert(out.Grid()->Nd() == in.Grid()->Nd());
for(int d=0;d<out.Grid()->Nd();d++){
@ -1145,6 +1146,128 @@ void precisionChange(Lattice<VobjOut> &out, const Lattice<VobjIn> &in)
});
}
//The workspace for a precision change operation allowing for the reuse of the mapping to save time on subsequent calls
class precisionChangeWorkspace{
std::pair<Integer,Integer>* fmap_device; //device pointer
//maintain grids for checking
GridBase* _out_grid;
GridBase* _in_grid;
public:
precisionChangeWorkspace(GridBase *out_grid, GridBase *in_grid): _out_grid(out_grid), _in_grid(in_grid){
//Build a map between the sites and lanes of the output field and the input field as we cannot use the Grids on the device
assert(out_grid->Nd() == in_grid->Nd());
for(int d=0;d<out_grid->Nd();d++){
assert(out_grid->FullDimensions()[d] == in_grid->FullDimensions()[d]);
}
int Nsimd_out = out_grid->Nsimd();
std::vector<Coordinate> out_icorrs(out_grid->Nsimd()); //reuse these
for(int lane=0; lane < out_grid->Nsimd(); lane++)
out_grid->iCoorFromIindex(out_icorrs[lane], lane);
std::vector<std::pair<Integer,Integer> > fmap_host(out_grid->lSites()); //lsites = osites*Nsimd
thread_for(out_oidx,out_grid->oSites(),{
Coordinate out_ocorr;
out_grid->oCoorFromOindex(out_ocorr, out_oidx);
Coordinate lcorr; //the local coordinate (common to both in and out as full coordinate)
for(int out_lane=0; out_lane < Nsimd_out; out_lane++){
out_grid->InOutCoorToLocalCoor(out_ocorr, out_icorrs[out_lane], lcorr);
//int in_oidx = in_grid->oIndex(lcorr), in_lane = in_grid->iIndex(lcorr);
//Note oIndex and OcorrFromOindex (and same for iIndex) are not inverse for checkerboarded lattice, the former coordinates being defined on the full lattice and the latter on the reduced lattice
//Until this is fixed we need to circumvent the problem locally. Here I will use the coordinates defined on the reduced lattice for simplicity
int in_oidx = 0, in_lane = 0;
for(int d=0;d<in_grid->_ndimension;d++){
in_oidx += in_grid->_ostride[d] * ( lcorr[d] % in_grid->_rdimensions[d] );
in_lane += in_grid->_istride[d] * ( lcorr[d] / in_grid->_rdimensions[d] );
}
fmap_host[out_lane + Nsimd_out*out_oidx] = std::pair<Integer,Integer>( in_oidx, in_lane );
}
});
//Copy the map to the device (if we had a way to tell if an accelerator is in use we could avoid this copy for CPU-only machines)
size_t fmap_bytes = out_grid->lSites() * sizeof(std::pair<Integer,Integer>);
fmap_device = (std::pair<Integer,Integer>*)acceleratorAllocDevice(fmap_bytes);
acceleratorCopyToDevice(fmap_host.data(), fmap_device, fmap_bytes);
}
//Prevent moving or copying
precisionChangeWorkspace(const precisionChangeWorkspace &r) = delete;
precisionChangeWorkspace(precisionChangeWorkspace &&r) = delete;
precisionChangeWorkspace &operator=(const precisionChangeWorkspace &r) = delete;
precisionChangeWorkspace &operator=(precisionChangeWorkspace &&r) = delete;
std::pair<Integer,Integer> const* getMap() const{ return fmap_device; }
void checkGrids(GridBase* out, GridBase* in) const{
conformable(out, _out_grid);
conformable(in, _in_grid);
}
~precisionChangeWorkspace(){
acceleratorFreeDevice(fmap_device);
}
};
//We would like to use precisionChangeFast when possible. However usage of this requires the Grids to be the same (runtime check)
//*and* the precisionChange(VobjOut::vector_type, VobjIn, int) function to be defined for the types; this requires an extra compile-time check which we do using some SFINAE trickery
template<class VobjOut, class VobjIn>
auto _precisionChangeFastWrap(Lattice<VobjOut> &out, const Lattice<VobjIn> &in, int dummy)->decltype( precisionChange( ((typename VobjOut::vector_type*)0), ((typename VobjIn::vector_type*)0), 1), int()){
if(out.Grid() == in.Grid()){
precisionChangeFast(out,in);
return 1;
}else{
return 0;
}
}
template<class VobjOut, class VobjIn>
int _precisionChangeFastWrap(Lattice<VobjOut> &out, const Lattice<VobjIn> &in, long dummy){ //note long here is intentional; it means the above is preferred if available
return 0;
}
//Convert a lattice of one precision to another. Much faster than original implementation but requires a pregenerated workspace
//which contains the mapping data.
template<class VobjOut, class VobjIn>
void precisionChange(Lattice<VobjOut> &out, const Lattice<VobjIn> &in, const precisionChangeWorkspace &workspace){
if(_precisionChangeFastWrap(out,in,0)) return;
static_assert( std::is_same<typename VobjOut::scalar_typeD, typename VobjIn::scalar_typeD>::value == 1, "precisionChange: tensor types must be the same" ); //if tensor types are same the DoublePrecision type must be the same
out.Checkerboard() = in.Checkerboard();
constexpr int Nsimd_out = VobjOut::Nsimd();
workspace.checkGrids(out.Grid(),in.Grid());
std::pair<Integer,Integer> const* fmap_device = workspace.getMap();
//Do the copy/precision change
autoView( out_v , out, AcceleratorWrite);
autoView( in_v , in, AcceleratorRead);
accelerator_for(out_oidx, out.Grid()->oSites(), 1,{
std::pair<Integer,Integer> const* fmap_osite = fmap_device + out_oidx*Nsimd_out;
for(int out_lane=0; out_lane < Nsimd_out; out_lane++){
int in_oidx = fmap_osite[out_lane].first;
int in_lane = fmap_osite[out_lane].second;
copyLane(out_v[out_oidx], out_lane, in_v[in_oidx], in_lane);
}
});
}
//Convert a Lattice from one precision to another. Much faster than original implementation but slower than precisionChangeFast
//or precisionChange called with pregenerated workspace, as it needs to internally generate the workspace on the host and copy to device
template<class VobjOut, class VobjIn>
void precisionChange(Lattice<VobjOut> &out, const Lattice<VobjIn> &in){
if(_precisionChangeFastWrap(out,in,0)) return;
precisionChangeWorkspace workspace(out.Grid(), in.Grid());
precisionChange(out, in, workspace);
}
////////////////////////////////////////////////////////////////////////////////
// Communicate between grids
////////////////////////////////////////////////////////////////////////////////