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[Draft] Fix: MPI-Distribution w/o SC
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Without space charge, we can simply split the particles up during
init in equal chunks and leave them there forever.

This fixes grid generation by setting the `max_grid_size` to the
AMReX `blocking_factor` (if not set by the user). Also, this
avoids all calls to `ResizeMesh()` and `Redistribute` for now.
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@ax3l
ax3l committed Jan 23, 2024
1 parent 3b1822d commit 983dde4
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Showing 4 changed files with 50 additions and 11 deletions.
27 changes: 23 additions & 4 deletions src/ImpactX.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -55,13 +55,14 @@ namespace impactx
{
BL_PROFILE("ImpactX::initGrids");

// In init_amr_core, when
// n_cells has been set using temporary values earlier. We now know the true value of
// n_cells, so we recompute the Geometry objects for each level here *if* the user
// has set n_cells in the inputs file
{
amrex::Vector<int> n_cell(AMREX_SPACEDIM);
amrex::ParmParse const pp_amr("amr");
pp_amr.queryarr("n_cell", n_cell);
pp_amr.getarr("n_cell", n_cell);

amrex::IntVect const lo(amrex::IntVect::TheZeroVector());
amrex::IntVect hi(n_cell);
Expand Down Expand Up @@ -176,13 +177,18 @@ namespace impactx
for (int slice_step = 0; slice_step < nslice; ++slice_step) {
BL_PROFILE("ImpactX::evolve::slice_step");
global_step++;
auto const global_np = m_particle_container->TotalNumberOfParticles(false, false);
auto const local_np = m_particle_container->TotalNumberOfParticles(false, true);

amrex::Print() << " ++++ Starting global_step=" << global_step
<< " slice_step=" << slice_step << "\n";

// Space-charge calculation: turn off if there is only 1 particle
if (space_charge &&
m_particle_container->TotalNumberOfParticles(false, false) > 1) {
amrex::AllPrint() << "Local np=" << local_np << " out of global np=" << global_np
<< " at Proc=" << amrex::ParallelDescriptor::MyProc() << "\n";

// Space-charge calculation: turn off if there is only 1 particle
if (space_charge && global_np > 1)
{
// transform from x',y',t to x,y,z
transformation::CoordinateTransformation(
*m_particle_container,
Expand Down Expand Up @@ -220,6 +226,19 @@ namespace impactx
transformation::CoordinateTransformation(*m_particle_container,
CoordSystem::s);
}
// balance particle beam in sims w/o space charge
/*else if (global_np > 1)
{
// Resize the mesh, based on `m_particle_container` extent
amrex::ParmParse pp_geometry("geometry");
amrex::Vector<amrex::Real> prob_relative(max_level + 1, 1.0);
pp_geometry.addarr("prob_relative", prob_relative);
ResizeMesh();
// Redistribute particles in the new mesh in x, y, t
m_particle_container->Redistribute();
}*/

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// for later: original Impact implementation as an option
// Redistribute particles in x',y',t
Expand Down
22 changes: 18 additions & 4 deletions src/initialization/InitAmrCore.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,7 @@ namespace details

amrex::Vector<int> n_cell(AMREX_SPACEDIM);
bool const has_ncell = pp_amr.queryarr("n_cell", n_cell);
amrex::Print() << "has_ncell=" << has_ncell << "\n";
if (has_ncell)
return amrex_amrcore_gridding();
else
Expand All @@ -88,8 +89,9 @@ namespace details
{
amrex::ParmParse const pp_amr("amr");

// Domain index space - we use temporary values here, then fix later
amrex::Vector<int> const n_cell = {AMREX_D_DECL(256,256,256)};
// Domain index space
amrex::Vector<int> n_cell;
pp_amr.getarr("n_cell", n_cell);
amrex::Box const domain(amrex::IntVect(0), amrex::IntVect(n_cell));

// Domain physical size
Expand All @@ -111,14 +113,26 @@ namespace details
AmrCoreData
one_box_per_rank ()
{
// Domain index space
amrex::AmrInfo amr_info;

// set max_grid_size to blocking_factor to fix the number of boxes we generate
amrex::ParmParse pp_amr("amr");
bool const has_max_grid_size =
pp_amr.countRecords("max_grid_size") > 0 ||
pp_amr.countRecords("max_grid_size_x") > 0 ||
pp_amr.countRecords("max_grid_size_y") > 0 ||
pp_amr.countRecords("max_grid_size_z") > 0;
if (!has_max_grid_size) {
amrex::Vector<int> const bf_lvl0(amr_info.blocking_factor[0].begin(), amr_info.blocking_factor[0].end());
pp_amr.addarr("max_grid_size", bf_lvl0);
}

// Domain index space
const int nprocs = amrex::ParallelDescriptor::NProcs();
const amrex::IntVect high_end = amr_info.blocking_factor[0]
* amrex::IntVect(AMREX_D_DECL(nprocs,1,1)) - amrex::IntVect(1);
amrex::Box const domain(amrex::IntVect(0), high_end);
// adding amr.n_cell for consistency
amrex::ParmParse pp_amr("amr");
auto const n_cell_iv = domain.size();
amrex::Vector<int> const n_cell_v(n_cell_iv.begin(), n_cell_iv.end());
pp_amr.addarr("n_cell", n_cell_v);
Expand Down
4 changes: 2 additions & 2 deletions src/initialization/InitDistribution.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -109,8 +109,8 @@ namespace impactx
// Resize the mesh to fit the spatial extent of the beam and then
// redistribute particles, so they reside on the MPI rank that is
// responsible for the respective spatial particle position.
this->ResizeMesh();
m_particle_container->Redistribute();
//this->ResizeMesh();
//m_particle_container->Redistribute();
}

void ImpactX::initBeamDistributionFromInputs ()
Expand Down
8 changes: 7 additions & 1 deletion src/initialization/InitMeshRefinement.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -32,9 +32,13 @@ namespace detail
amrex::Vector<amrex::Real>
read_mr_prob_relative ()
{
amrex::ParmParse pp_algo("algo");
amrex::ParmParse pp_amr("amr");
amrex::ParmParse pp_geometry("geometry");

bool space_charge = false;
pp_algo.query("space_charge", space_charge);

int max_level = 0;
pp_amr.query("max_level", max_level);

Expand All @@ -43,7 +47,7 @@ namespace detail
prob_relative[0] = 3.0; // top/bottom pad the beam on the lowest level by default by its width
pp_geometry.queryarr("prob_relative", prob_relative);

if (prob_relative[0] < 3.0)
if (prob_relative[0] < 3.0 && space_charge)
ablastr::warn_manager::WMRecordWarning(
"ImpactX::read_mr_prob_relative",
"Dynamic resizing of the mesh uses a geometry.prob_relative "
Expand Down Expand Up @@ -315,6 +319,8 @@ namespace detail
g.ProbDomain(rb[lev]);
SetGeometry(lev, g);

amrex::AllPrint() << "lev=" << lev << " Geometry=" << g << "\n";

m_particle_container->SetParticleGeometry(lev, g);
}
}
Expand Down

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