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LST CPU Speedups #245

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LST CPU Speedups #245

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2375562
remove redundant memory loads
GNiendorf Mar 19, 2026
117c197
pre-checks, exact trig simplifications, and additional early exits
GNiendorf Mar 27, 2026
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2 changes: 1 addition & 1 deletion HeterogeneousCore/AlpakaMath/interface/deltaPhi.h
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@ namespace cms::alpakatools {

template <alpaka::concepts::Acc TAcc, typename T>
ALPAKA_FN_HOST_ACC inline T deltaPhi(TAcc const& acc, T x1, T y1, T x2, T y2) {
return reducePhiRange(acc, alpaka::math::atan2(acc, -y2, -x2) - alpaka::math::atan2(acc, -y1, -x1));
return alpaka::math::atan2(acc, x1 * y2 - x2 * y1, x1 * x2 + y1 * y2);
}

template <alpaka::concepts::Acc TAcc, typename T>
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1 change: 1 addition & 0 deletions RecoTracker/LSTCore/interface/alpaka/Common.h
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Expand Up @@ -40,6 +40,7 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
HOST_DEVICE_CONSTANT float kStripPSZpitch = 2.4;
HOST_DEVICE_CONSTANT float kStrip2SZpitch = 5.0;
HOST_DEVICE_CONSTANT float kWidth2S = 0.009;
HOST_DEVICE_CONSTANT float kDisks2SMinRadius = 60.0;
HOST_DEVICE_CONSTANT float kWidthPS = 0.01;
HOST_DEVICE_CONSTANT float kPt_betaMax = 7.0;
HOST_DEVICE_CONSTANT int kNTripletThreshold = 1000;
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39 changes: 23 additions & 16 deletions RecoTracker/LSTCore/src/alpaka/Kernels.h
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Expand Up @@ -247,7 +247,10 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
if (quintuplets.isDup()[ix] & 1)
continue;

bool isPT5_ix = quintuplets.partOfPT5()[ix];
const bool isPT5_ix = quintuplets.partOfPT5()[ix];
const float eta1 = __H2F(quintuplets.eta()[ix]);
const float phi1 = __H2F(quintuplets.phi()[ix]);
const float score_rphisum1 = __H2F(quintuplets.score_rphisum()[ix]);

for (unsigned int jx1 = 0; jx1 < nQuintuplets_lowmod2; jx1++) {
unsigned int jx = quintupletModuleIndices_lowmod2 + jx1;
Expand All @@ -257,31 +260,24 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
if (quintuplets.isDup()[jx] & 1)
continue;

bool isPT5_jx = quintuplets.partOfPT5()[jx];
const bool isPT5_jx = quintuplets.partOfPT5()[jx];

if (isPT5_ix && isPT5_jx)
continue;

float eta1 = __H2F(quintuplets.eta()[ix]);
float phi1 = __H2F(quintuplets.phi()[ix]);
float score_rphisum1 = __H2F(quintuplets.score_rphisum()[ix]);

float eta2 = __H2F(quintuplets.eta()[jx]);
float phi2 = __H2F(quintuplets.phi()[jx]);
float score_rphisum2 = __H2F(quintuplets.score_rphisum()[jx]);

float dEta = alpaka::math::abs(acc, eta1 - eta2);
float dPhi = cms::alpakatools::deltaPhi(acc, phi1, phi2);

const float eta2 = __H2F(quintuplets.eta()[jx]);
const float dEta = alpaka::math::abs(acc, eta1 - eta2);
if (dEta > 0.1f)
continue;

const float phi2 = __H2F(quintuplets.phi()[jx]);
const float dPhi = cms::alpakatools::deltaPhi(acc, phi1, phi2);
if (alpaka::math::abs(acc, dPhi) > 0.1f)
continue;

float dR2 = dEta * dEta + dPhi * dPhi;
int nMatched = checkHitsT5(ix, jx, quintuplets);
const int minNHitsForDup_T5 = 5;
const float dR2 = dEta * dEta + dPhi * dPhi;
const int nMatched = checkHitsT5(ix, jx, quintuplets);
constexpr int minNHitsForDup_T5 = 5;

float d2 = 0.f;
CMS_UNROLL_LOOP
Expand All @@ -291,6 +287,7 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
}

if (((dR2 < 0.001f || nMatched >= minNHitsForDup_T5) && d2 < 1.0f) || (dR2 < 0.02f && d2 < 0.1f)) {
const float score_rphisum2 = __H2F(quintuplets.score_rphisum()[jx]);
if (isPT5_jx || score_rphisum1 > score_rphisum2) {
rmQuintupletFromMemory(quintuplets, ix, true);
} else if (isPT5_ix || score_rphisum1 < score_rphisum2) {
Expand Down Expand Up @@ -458,11 +455,21 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
ALPAKA_FN_ACC void operator()(Acc2D const& acc, PixelQuintuplets pixelQuintuplets) const {
unsigned int nPixelQuintuplets = pixelQuintuplets.nPixelQuintuplets();
for (unsigned int ix : cms::alpakatools::uniform_elements_y(acc, nPixelQuintuplets)) {
float eta1 = __H2F(pixelQuintuplets.eta()[ix]);
float phi1 = __H2F(pixelQuintuplets.phi()[ix]);
float score1 = __H2F(pixelQuintuplets.score()[ix]);
for (unsigned int jx : cms::alpakatools::uniform_elements_x(acc, nPixelQuintuplets)) {
if (ix == jx)
continue;

float eta2 = __H2F(pixelQuintuplets.eta()[jx]);
if (alpaka::math::abs(acc, eta1 - eta2) > 0.2f)
continue;

float phi2 = __H2F(pixelQuintuplets.phi()[jx]);
if (alpaka::math::abs(acc, cms::alpakatools::deltaPhi(acc, phi1, phi2)) > 0.2f)
continue;

int nMatched = checkHitspT5(ix, jx, pixelQuintuplets);
float score2 = __H2F(pixelQuintuplets.score()[jx]);
const int minNHitsForDup_pT5 = 7;
Expand Down
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