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ITS: GPU: overlap memcpy with compute kernels #14596

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Merged
mconcas merged 1 commit into from
Aug 18, 2025
Merged

ITS: GPU: overlap memcpy with compute kernels #14596

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36 changes: 24 additions & 12 deletions Detectors/ITSMFT/ITS/tracking/GPU/cuda/TrackerTraitsGPU.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -60,18 +60,23 @@ void TrackerTraitsGPU<nLayers>::computeLayerTracklets(const int iteration, int i
int startROF{this->mTrkParams[iteration].nROFsPerIterations > 0 ? iROFslice * this->mTrkParams[iteration].nROFsPerIterations : 0};
int endROF{o2::gpu::CAMath::Min(this->mTrkParams[iteration].nROFsPerIterations > 0 ? (iROFslice + 1) * this->mTrkParams[iteration].nROFsPerIterations + this->mTrkParams[iteration].DeltaROF : mTimeFrameGPU->getNrof(), mTimeFrameGPU->getNrof())};

for (int iLayer = 0; iLayer < nLayers; ++iLayer) {
// TODO lazy loading of essential data on separate streams
// start by queuing loading needed of two last layers
for (int iLayer{nLayers}; iLayer-- > nLayers - 2;) {
mTimeFrameGPU->createUsedClustersDevice(iteration, iLayer);
mTimeFrameGPU->loadClustersDevice(iteration, iLayer);
mTimeFrameGPU->loadUnsortedClustersDevice(iteration, iLayer);
mTimeFrameGPU->loadClustersIndexTables(iteration, iLayer);
mTimeFrameGPU->loadROFrameClustersDevice(iteration, iLayer);
mTimeFrameGPU->recordEvent(iLayer);
}

// processing starts here
for (int iLayer{0}; iLayer < this->mTrkParams[iteration].TrackletsPerRoad(); ++iLayer) {
for (int iLayer{this->mTrkParams[iteration].TrackletsPerRoad()}; iLayer--;) {
if (iLayer) { // queue loading data of next layer in parallel, this the copies are overlapping with computation kernels
mTimeFrameGPU->createUsedClustersDevice(iteration, iLayer - 1);
mTimeFrameGPU->loadClustersDevice(iteration, iLayer - 1);
mTimeFrameGPU->loadClustersIndexTables(iteration, iLayer - 1);
mTimeFrameGPU->loadROFrameClustersDevice(iteration, iLayer - 1);
mTimeFrameGPU->recordEvent(iLayer - 1);
}
mTimeFrameGPU->createTrackletsLUTDevice(iteration, iLayer);
mTimeFrameGPU->waitEvent(iLayer, iLayer + 1); // wait stream until all data is available
countTrackletsInROFsHandler<nLayers>(mTimeFrameGPU->getDeviceIndexTableUtils(),
Expand All @@ -91,7 +96,7 @@ void TrackerTraitsGPU<nLayers>::computeLayerTracklets(const int iteration, int i
mTimeFrameGPU->getDeviceArrayUsedClusters(),
mTimeFrameGPU->getDeviceArrayClustersIndexTables(),
mTimeFrameGPU->getDeviceArrayTrackletsLUT(),
mTimeFrameGPU->getDeviceTrackletsLUTs(), // Required for the exclusive sums
mTimeFrameGPU->getDeviceTrackletsLUTs(),
iteration,
this->mTrkParams[iteration].NSigmaCut,
mTimeFrameGPU->getPhiCuts(),
Expand All @@ -107,7 +112,7 @@ void TrackerTraitsGPU<nLayers>::computeLayerTracklets(const int iteration, int i
mTimeFrameGPU->getStreams());
mTimeFrameGPU->createTrackletsBuffers(iLayer);
if (mTimeFrameGPU->getNTracklets()[iLayer] == 0) {
return;
continue;
}
computeTrackletsInROFsHandler<nLayers>(mTimeFrameGPU->getDeviceIndexTableUtils(),
mTimeFrameGPU->getDeviceMultCutMask(),
Expand Down Expand Up @@ -151,18 +156,25 @@ void TrackerTraitsGPU<nLayers>::computeLayerCells(const int iteration)
{
auto& conf = o2::its::ITSGpuTrackingParamConfig::Instance();

for (int iLayer = 0; iLayer < nLayers; ++iLayer) {
// TODO lazy loading of essential data on separate streams
// start by queuing loading needed of three last layers
for (int iLayer{nLayers}; iLayer-- > nLayers - 3;) {
mTimeFrameGPU->loadUnsortedClustersDevice(iteration, iLayer);
mTimeFrameGPU->loadTrackingFrameInfoDevice(iteration, iLayer);
mTimeFrameGPU->recordEvent(iLayer);
}

for (int iLayer{0}; iLayer < this->mTrkParams[iteration].CellsPerRoad(); ++iLayer) {
for (int iLayer{this->mTrkParams[iteration].CellsPerRoad()}; iLayer--;) {
if (iLayer) {
mTimeFrameGPU->loadUnsortedClustersDevice(iteration, iLayer - 1);
mTimeFrameGPU->loadTrackingFrameInfoDevice(iteration, iLayer - 1);
mTimeFrameGPU->recordEvent(iLayer - 1);
}

// if there are no tracklets skip entirely
const int currentLayerTrackletsNum{static_cast<int>(mTimeFrameGPU->getNTracklets()[iLayer])};
if (!currentLayerTrackletsNum || !mTimeFrameGPU->getNTracklets()[iLayer + 1]) {
mTimeFrameGPU->getNCells()[iLayer] = 0;
return;
continue;
}

mTimeFrameGPU->createCellsLUTDevice(iLayer);
Expand All @@ -189,7 +201,7 @@ void TrackerTraitsGPU<nLayers>::computeLayerCells(const int iteration)
mTimeFrameGPU->getStreams());
mTimeFrameGPU->createCellsBuffers(iLayer);
if (mTimeFrameGPU->getNCells()[iLayer] == 0) {
return;
continue;
}
computeCellsHandler(mTimeFrameGPU->getDeviceArrayClusters(),
mTimeFrameGPU->getDeviceArrayUnsortedClusters(),
Expand Down