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ariedel-cernariedel-cern
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Feat: speed up event mixing in triplet tasks
1 parent c0272aa commit f80000d

1 file changed

Lines changed: 44 additions & 18 deletions

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‎PWGCF/Femto/Core/tripletProcessHelpers.h‎

Lines changed: 44 additions & 18 deletions
Original file line numberDiff line numberDiff line change
@@ -459,20 +459,34 @@ void processMixedEvent(T1 const& Collisions,
459459
T10& CtrManager,
460460
T11& TcManager)
461461
{
462-
int64_t lastCollisionIndex = -1;
462+
int64_t lastCollisionIndex1 = -1;
463+
int64_t lastCollisionIndex2 = -1;
463464
int windowSizeRaw = 0;
464465
int windowSizeEffective = 0;
465466

467+
// collision1 stays fixed across the outer mixing window, and collision2 stays fixed across each inner sub-window (it only advances once collision3 wraps
468+
// back to its start Both slices are therefore materialized once per window/sub-window and reused, instead of being re-sliced, i.e. a fresh arrow Slice + selection copy
469+
std::optional<decltype(Partition1->sliceByCached(o2::aod::femtobase::stored::fColId, 0, cache))> sliceParticle1;
470+
std::optional<decltype(Partition2->sliceByCached(o2::aod::femtobase::stored::fColId, 0, cache))> sliceParticle2;
471+
466472
for (auto const& [collision1, collision2, collision3] : o2::soa::selfCombinations(policy, depth, -1, Collisions, Collisions, Collisions)) {
467473

468-
// --- new window ---
469-
if (collision1.globalIndex() != lastCollisionIndex) {
470-
if (lastCollisionIndex != -1) {
474+
// outer window
475+
if (collision1.globalIndex() != lastCollisionIndex1) {
476+
if (lastCollisionIndex1 != -1) {
471477
TripletHistManager.fillMixingQaMePerMixingBin(windowSizeRaw, windowSizeEffective);
472478
}
473479
windowSizeRaw = 0;
474480
windowSizeEffective = 0;
475-
lastCollisionIndex = collision1.globalIndex();
481+
lastCollisionIndex1 = collision1.globalIndex();
482+
lastCollisionIndex2 = -1; // force sliceParticle2 to refresh below
483+
sliceParticle1.emplace(Partition1->sliceByCached(o2::aod::femtobase::stored::fColId, collision1.globalIndex(), cache));
484+
}
485+
486+
// inner sub-window
487+
if (collision2.globalIndex() != lastCollisionIndex2) {
488+
lastCollisionIndex2 = collision2.globalIndex();
489+
sliceParticle2.emplace(Partition2->sliceByCached(o2::aod::femtobase::stored::fColId, collision2.globalIndex(), cache));
476490
}
477491

478492
++windowSizeRaw;
@@ -486,21 +500,19 @@ void processMixedEvent(T1 const& Collisions,
486500

487501
CtrManager.setMagField(collision1.magField());
488502

489-
auto sliceParticle1 = Partition1->sliceByCached(o2::aod::femtobase::stored::fColId, collision1.globalIndex(), cache);
490-
auto sliceParticle2 = Partition2->sliceByCached(o2::aod::femtobase::stored::fColId, collision2.globalIndex(), cache);
491503
auto sliceParticle3 = Partition3->sliceByCached(o2::aod::femtobase::stored::fColId, collision3.globalIndex(), cache);
492504

493505
TripletHistManager.resetTrackedParticlesPerEvent();
494506

495-
if (sliceParticle1.size() == 0 || sliceParticle2.size() == 0 || sliceParticle3.size() == 0) {
507+
if (sliceParticle1->size() == 0 || sliceParticle2->size() == 0 || sliceParticle3.size() == 0) {
496508
TripletHistManager.fillMixingQaMePerEvent();
497509
continue;
498510
}
499511

500512
bool hasValidTriplet = false;
501513
TripletHistManager.fillMixingQaMe(collision1, collision2, collision3);
502514

503-
for (auto const& [p1, p2, p3] : o2::soa::combinations(o2::soa::CombinationsFullIndexPolicy(sliceParticle1, sliceParticle2, sliceParticle3))) {
515+
for (auto const& [p1, p2, p3] : o2::soa::combinations(o2::soa::CombinationsFullIndexPolicy(*sliceParticle1, *sliceParticle2, sliceParticle3))) {
504516
// pair cleaning
505517
if (!TcManager.isCleanTriplet(p1, p2, p3, TrackTable)) {
506518
continue;
@@ -528,7 +540,7 @@ void processMixedEvent(T1 const& Collisions,
528540
TripletHistManager.fillMixingQaMePerEvent();
529541
}
530542

531-
// --- final window ---
543+
// final window
532544
if (windowSizeRaw > 0) {
533545
TripletHistManager.fillMixingQaMePerMixingBin(windowSizeRaw, windowSizeEffective);
534546
}
@@ -563,19 +575,34 @@ void processMixedEvent(T1 const& Collisions,
563575
T12& CtrManager,
564576
T13& TcManager)
565577
{
566-
int64_t lastCollisionIndex = -1;
578+
int64_t lastCollisionIndex1 = -1;
579+
int64_t lastCollisionIndex2 = -1;
567580
int windowSizeRaw = 0;
568581
int windowSizeEffective = 0;
569582

583+
// collision1 stays fixed across the outer mixing window, and collision2 stays fixed across each inner sub-window (it only advances once collision3 wraps
584+
// back to its start Both slices are therefore materialized once per window/sub-window and reused, instead of being re-sliced, i.e. a fresh arrow Slice + selection copy
585+
std::optional<decltype(Partition1->sliceByCached(o2::aod::femtobase::stored::fColId, 0, cache))> sliceParticle1;
586+
std::optional<decltype(Partition2->sliceByCached(o2::aod::femtobase::stored::fColId, 0, cache))> sliceParticle2;
587+
570588
for (auto const& [collision1, collision2, collision3] : o2::soa::selfCombinations(policy, depth, -1, Collisions, Collisions, Collisions)) {
571589

572-
if (collision1.globalIndex() != lastCollisionIndex) {
573-
if (lastCollisionIndex != -1) {
590+
// outer window
591+
if (collision1.globalIndex() != lastCollisionIndex1) {
592+
if (lastCollisionIndex1 != -1) {
574593
TripletHistManager.fillMixingQaMePerMixingBin(windowSizeRaw, windowSizeEffective);
575594
}
576595
windowSizeRaw = 0;
577596
windowSizeEffective = 0;
578-
lastCollisionIndex = collision1.globalIndex();
597+
lastCollisionIndex1 = collision1.globalIndex();
598+
lastCollisionIndex2 = -1; // force sliceParticle2 to refresh below
599+
sliceParticle1.emplace(Partition1->sliceByCached(o2::aod::femtobase::stored::fColId, collision1.globalIndex(), cache));
600+
}
601+
602+
// inner sub-window
603+
if (collision2.globalIndex() != lastCollisionIndex2) {
604+
lastCollisionIndex2 = collision2.globalIndex();
605+
sliceParticle2.emplace(Partition2->sliceByCached(o2::aod::femtobase::stored::fColId, collision2.globalIndex(), cache));
579606
}
580607

581608
++windowSizeRaw;
@@ -589,21 +616,19 @@ void processMixedEvent(T1 const& Collisions,
589616

590617
CtrManager.setMagField(collision1.magField());
591618

592-
auto sliceParticle1 = Partition1->sliceByCached(o2::aod::femtobase::stored::fColId, collision1.globalIndex(), cache);
593-
auto sliceParticle2 = Partition2->sliceByCached(o2::aod::femtobase::stored::fColId, collision2.globalIndex(), cache);
594619
auto sliceParticle3 = Partition3->sliceByCached(o2::aod::femtobase::stored::fColId, collision3.globalIndex(), cache);
595620

596621
TripletHistManager.resetTrackedParticlesPerEvent();
597622

598-
if (sliceParticle1.size() == 0 || sliceParticle2.size() == 0 || sliceParticle3.size() == 0) {
623+
if (sliceParticle1->size() == 0 || sliceParticle2->size() == 0 || sliceParticle3.size() == 0) {
599624
TripletHistManager.fillMixingQaMePerEvent();
600625
continue;
601626
}
602627

603628
bool hasValidTriplet = false;
604629
TripletHistManager.fillMixingQaMe(collision1, collision2, collision3);
605630

606-
for (auto const& [p1, p2, p3] : o2::soa::combinations(o2::soa::CombinationsFullIndexPolicy(sliceParticle1, sliceParticle2, sliceParticle3))) {
631+
for (auto const& [p1, p2, p3] : o2::soa::combinations(o2::soa::CombinationsFullIndexPolicy(*sliceParticle1, *sliceParticle2, sliceParticle3))) {
607632
// pair cleaning
608633
if (!TcManager.isCleanTriplet(p1, p2, p3, TrackTable)) {
609634
continue;
@@ -631,6 +656,7 @@ void processMixedEvent(T1 const& Collisions,
631656
TripletHistManager.fillMixingQaMePerEvent();
632657
}
633658

659+
// --- final window ---
634660
if (windowSizeRaw > 0) {
635661
TripletHistManager.fillMixingQaMePerMixingBin(windowSizeRaw, windowSizeEffective);
636662
}

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