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Improved performance of G-parity kernel for GPUs by simplifying multLink implementation

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This commit is contained in:
Christopher Kelly 2020-12-07 11:53:35 -05:00
parent 888eacd3b8
commit 2ef1fa66a8
1 changed files with 15 additions and 27 deletions
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42
Grid/qcd/action/fermion/GparityWilsonImpl.h
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@ -97,42 +97,30 @@ public:
Coordinate icoor;
#ifdef GRID_SIMT
_Spinor tmp;
const int Nsimd =SiteDoubledGaugeField::Nsimd();
int s = acceleratorSIMTlane(Nsimd);
St.iCoorFromIindex(icoor,s);
int mmu = mu % Nd;
if ( SE->_around_the_world && St.parameters.twists[mmu] ) {
int permute_lane = (sl==1)
|| ((distance== 1)&&(icoor[direction]==1))
|| ((distance==-1)&&(icoor[direction]==0));
if ( permute_lane ) {
tmp(0) = chi(1);
tmp(1) = chi(0);
} else {
tmp(0) = chi(0);
tmp(1) = chi(1);
}
auto UU0=coalescedRead(U(0)(mu));
auto UU1=coalescedRead(U(1)(mu));
//Decide whether we do a G-parity flavor twist
//Note: this assumes (but does not check) that sl==1 || sl==2 i.e. max 2 SIMD lanes in G-parity dir
//It also assumes (but does not check) that abs(distance) == 1
int permute_lane = (sl==1)
|| ((distance== 1)&&(icoor[direction]==1))
|| ((distance==-1)&&(icoor[direction]==0));
auto UU0=coalescedRead(U(0)(mu));
auto UU1=coalescedRead(U(1)(mu));
permute_lane = permute_lane && SE->_around_the_world && St.parameters.twists[mmu]; //only if we are going around the world
mult(&phi(0),&UU0,&tmp(0));
mult(&phi(1),&UU1,&tmp(1));
//Apply the links
int f_upper = permute_lane ? 1 : 0;
int f_lower = !f_upper;
} else {
auto UU0=coalescedRead(U(0)(mu));
auto UU1=coalescedRead(U(1)(mu));
mult(&phi(0),&UU0,&chi(0));
mult(&phi(1),&UU1,&chi(1));
}
mult(&phi(0),&UU0,&chi(f_upper));
mult(&phi(1),&UU1,&chi(f_lower));
#else
typedef _Spinor vobj;