Commit dc602245 authored by Matthieu Schaller's avatar Matthieu Schaller
Browse files

Use the threadpool and atomic operations to parallelize the assignment of...

Use the threadpool and atomic operations to parallelize the assignment of gparts to the density mesh.
parent 6d9622a0
......@@ -3935,7 +3935,7 @@ void engine_rebuild(struct engine *e, int clean_smoothing_length_values) {
/* Re-compute the mesh forces */
if ((e->policy & engine_policy_self_gravity) && e->s->periodic)
pm_mesh_compute_potential(e->mesh, e->s, e->verbose);
pm_mesh_compute_potential(e->mesh, e->s, &e->threadpool, e->verbose);
/* Re-compute the maximal RMS displacement constraint */
if (e->policy & engine_policy_cosmology)
......
......@@ -193,6 +193,48 @@ void cell_gpart_to_mesh_CIC(const struct cell* c, double* rho, int N,
gpart_to_mesh_CIC(&gparts[i], rho, N, fac, dim);
}
/**
* @brief Shared information about the mesh to be used by all the threads in the pool.
*/
struct cic_mapper_data{
const struct cell *cells;
double *rho;
int N;
double fac;
double dim[3];
};
/**
* @brief Threadpool mapper function for the mesh CIC assignment of a cell.
*
* @param map_data A chunk of the list of local cells.
* @param num The number of cells in the chunk.
* @param extra The information about the mesh and cells.
*/
void cell_gpart_to_mesh_CIC_mapper(void *map_data, int num, void* extra) {
/* Unpack the shared information */
const struct cic_mapper_data *data = (struct cic_mapper_data*) extra;
const struct cell *cells = data->cells;
double *rho = data->rho;
const int N = data->N;
const double fac = data->fac;
const double dim[3] = {data->dim[0], data->dim[1], data->dim[2]};
/* Pointer to the chunk to be processed */
int *local_cells = (int *)map_data;
/* Loop over the elements assigned to this thread */
for (int i = 0; i < num; ++i) {
/* Pointer to local cell */
const struct cell *c = &cells[local_cells[i]];
/* Assign this cell's content to the mesh */
cell_gpart_to_mesh_CIC(c, rho, N, fac, dim);
}
}
/**
* @brief Computes the potential on a gpart from a given mesh using the CIC
* method.
......@@ -310,14 +352,13 @@ void mesh_to_gparts_CIC(struct gpart* gp, const double* pot, int N, double fac,
* @param verbose Are we talkative?
*/
void pm_mesh_compute_potential(struct pm_mesh* mesh, const struct space* s,
int verbose) {
struct threadpool *tp, int verbose) {
#ifdef HAVE_FFTW
const double r_s = mesh->r_s;
const double box_size = s->dim[0];
const double dim[3] = {s->dim[0], s->dim[1], s->dim[2]};
const struct cell* cells = s->cells_top;
const int* local_cells = s->local_cells_top;
const int nr_local_cells = s->nr_local_cells;
......@@ -350,10 +391,20 @@ void pm_mesh_compute_potential(struct pm_mesh* mesh, const struct space* s,
/* Zero everything */
bzero(rho, N * N * N * sizeof(double));
/* Do a CIC mesh assignment of the gparts by looping over local top-level
* cells */
for (int k = 0; k < nr_local_cells; k++)
cell_gpart_to_mesh_CIC(&cells[local_cells[k]], rho, N, cell_fac, dim);
/* Gather the mesh shared information to be used by the threads */
struct cic_mapper_data data;
data.cells = s->cells_top;
data.rho = rho;
data.N = N;
data.fac = cell_fac;
data.dim[0] = dim[0];
data.dim[1] = dim[1];
data.dim[2] = dim[2];
/* Do a parallel CIC mesh assignment of the gparts but only using
the local top-level cells */
threadpool_map(tp, cell_gpart_to_mesh_CIC_mapper, (void*) local_cells,
nr_local_cells, sizeof(int), 0, (void*) &data);
if (verbose)
message("Gpart assignment took %.3f %s.",
......
......@@ -29,6 +29,7 @@
/* Forward declarations */
struct space;
struct gpart;
struct threadpool;
/**
* @brief Data structure for the long-range periodic forces using a mesh
......@@ -67,7 +68,7 @@ void pm_mesh_init(struct pm_mesh *mesh, const struct gravity_props *props,
double dim[3]);
void pm_mesh_init_no_mesh(struct pm_mesh *mesh, double dim[3]);
void pm_mesh_compute_potential(struct pm_mesh *mesh, const struct space *s,
int verbose);
struct threadpool* tp, int verbose);
void pm_mesh_interpolate_forces(const struct pm_mesh *mesh,
const struct engine *e, struct gpart *gparts,
int gcount);
......
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