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Fixed the random number generator issue on large # of GPUs #177

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Merged
haykh merged 3 commits into from
Feb 9, 2026
Merged

Fixed the random number generator issue on large # of GPUs #177

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3028d2b
random pool is now std::optional
haykh Feb 9, 2026
fe3fea1
CPUTEST
haykh Feb 9, 2026
09b177b
bump cmake + order of variables in domain constructor
haykh Feb 9, 2026
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2 changes: 1 addition & 1 deletion CMakeLists.txt
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Original file line number Diff line number Diff line change
Expand Up @@ -7,7 +7,7 @@ set(PROJECT_NAME entity)

project(
${PROJECT_NAME}
VERSION 1.3.2
VERSION 1.3.3
LANGUAGES CXX C)
add_compile_options("-D ENTITY_VERSION=\"${PROJECT_VERSION}\"")
set(hash_cmd "git diff --quiet src/ && echo $(git rev-parse HEAD) ")
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4 changes: 2 additions & 2 deletions pgens/accretion/pgen.hpp
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Expand Up @@ -231,7 +231,7 @@ namespace user {

inline void InitPrtls(Domain<S, M>& local_domain) {
const auto energy_dist = arch::Maxwellian<S, M>(local_domain.mesh.metric,
local_domain.random_pool,
local_domain.random_pool(),
temperature);
const auto spatial_dist = PointDistribution<S, M>(xi_min,
xi_max,
Expand All @@ -252,7 +252,7 @@ namespace user {

void CustomPostStep(std::size_t, long double time, Domain<S, M>& local_domain) {
const auto energy_dist = arch::Maxwellian<S, M>(local_domain.mesh.metric,
local_domain.random_pool,
local_domain.random_pool(),
temperature);
const auto spatial_dist = PointDistribution<S, M>(xi_min,
xi_max,
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4 changes: 2 additions & 2 deletions pgens/reconnection/pgen.hpp
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Expand Up @@ -212,7 +212,7 @@ namespace user {

// current layer
auto edist_cs = arch::Maxwellian<S, M>(local_domain.mesh.metric,
local_domain.random_pool,
local_domain.random_pool(),
cs_temperature,
{ ZERO, ZERO, cs_drift_u });
const auto sdist_cs = CurrentLayer<S, M>(local_domain.mesh.metric,
Expand All @@ -239,7 +239,7 @@ namespace user {
}

const auto energy_dist = arch::Maxwellian<S, M>(domain.mesh.metric,
domain.random_pool,
domain.random_pool(),
bg_temperature);

const auto dx = domain.mesh.metric.template sqrt_h_<1, 1>({});
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2 changes: 1 addition & 1 deletion pgens/turbulence/pgen.hpp
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Expand Up @@ -398,7 +398,7 @@ namespace user {

// particle escape (resample velocities)
const auto energy_dist = arch::Maxwellian<S, M>(domain.mesh.metric,
domain.random_pool,
domain.random_pool(),
temperature);
for (const auto& sp : { 0, 1 }) {
if (domain.species[sp].npld_r() > 1) {
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4 changes: 2 additions & 2 deletions src/archetypes/particle_injector.h
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Expand Up @@ -254,7 +254,7 @@ namespace arch {
energy_dists.first,
energy_dists.second,
ONE / params.template get<real_t>("scales.V0"),
domain.random_pool));
domain.random_pool()));
domain.species[species.first - 1].set_npart(
domain.species[species.first - 1].npart() + nparticles);
domain.species[species.second - 1].set_npart(
Expand Down Expand Up @@ -372,7 +372,7 @@ namespace arch {
energy_dists.second,
spatial_dist,
ONE / params.template get<real_t>("scales.V0"),
domain.random_pool);
domain.random_pool());
Kokkos::parallel_for("InjectNonUniformNumberDensity",
cell_range,
injector_kernel);
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4 changes: 2 additions & 2 deletions src/archetypes/utils.h
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Expand Up @@ -53,11 +53,11 @@ namespace arch {
const auto temperature_2 = temperatures.second / mass_2;

const auto maxwellian_1 = arch::Maxwellian<S, M>(domain.mesh.metric,
domain.random_pool,
domain.random_pool(),
temperature_1,
drift_four_vels.first);
const auto maxwellian_2 = arch::Maxwellian<S, M>(domain.mesh.metric,
domain.random_pool,
domain.random_pool(),
temperature_2,
drift_four_vels.second);

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2 changes: 1 addition & 1 deletion src/engines/srpic.hpp
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Expand Up @@ -1291,7 +1291,7 @@ namespace ntt {
}

const auto maxwellian = arch::Maxwellian<S, M> { domain.mesh.metric,
domain.random_pool,
domain.random_pool(),
temp };

if (dim == in::x1) {
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19 changes: 15 additions & 4 deletions src/framework/domain/domain.h
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Original file line number Diff line number Diff line change
Expand Up @@ -53,6 +53,7 @@

#include <iomanip>
#include <map>
#include <optional>
#include <string>
#include <vector>

Expand All @@ -65,7 +66,6 @@ namespace ntt {
Mesh<M> mesh;
Fields<D, S> fields;
std::vector<Particles<D, M::CoordType>> species;
random_number_pool_t random_pool;

/**
* @brief constructor for "empty" allocation of non-local domain placeholders
Expand All @@ -81,7 +81,6 @@ namespace ntt {
: mesh { ncells, extent, metric_params }
, fields {}
, species {}
, random_pool { constant::RandomSeed }
, m_index { index }
, m_offset_ndomains { offset_ndomains }
, m_offset_ncells { offset_ncells } {}
Expand All @@ -96,10 +95,11 @@ namespace ntt {
: mesh { ncells, extent, metric_params }
, fields { ncells }
, species { species_params.begin(), species_params.end() }
, random_pool { constant::RandomSeed + static_cast<std::uint64_t>(index) }
, m_index { index }
, m_offset_ndomains { offset_ndomains }
, m_offset_ncells { offset_ncells } {}
, m_offset_ncells { offset_ncells }
, m_random_number_pool { constant::RandomSeed +
static_cast<std::uint64_t>(index) } {}

#if defined(MPI_ENABLED)
[[nodiscard]]
Expand Down Expand Up @@ -145,6 +145,14 @@ namespace ntt {
return fields.memory_footprint() == 0 and sp_footprint == 0;
}

[[nodiscard]]
auto random_pool() -> random_number_pool_t& {
raise::ErrorIf(not m_random_number_pool.has_value(),
"random_pool() called on a placeholder domain",
HERE);
return m_random_number_pool.value();
}

/* setters -------------------------------------------------------------- */
auto set_neighbor_idx(const dir::direction_t<D>& dir, unsigned int idx) -> void {
m_neighbor_idx[dir] = idx;
Expand All @@ -161,6 +169,9 @@ namespace ntt {
dir::map_t<D, unsigned int> m_neighbor_idx;
// MPI rank of the domain (used only when MPI enabled)
int m_mpi_rank;

// random number pool for the domain
std::optional<random_number_pool_t> m_random_number_pool;
};

template <SimEngine::type S, class M>
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