From 4c972cfc352ae5ba851cae142ca6fe594d88bc04 Mon Sep 17 00:00:00 2001 From: Anton Khirnov Date: Thu, 23 May 2019 11:01:00 +0200 Subject: egs: add support for MPI-based multi-component solves --- relax_mpi_test.c | 236 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 236 insertions(+) create mode 100644 relax_mpi_test.c (limited to 'relax_mpi_test.c') diff --git a/relax_mpi_test.c b/relax_mpi_test.c new file mode 100644 index 0000000..65888f6 --- /dev/null +++ b/relax_mpi_test.c @@ -0,0 +1,236 @@ +#include +#include +#include +#include +#include + +#include + +#include "components.h" +#include "ell_grid_solve.h" +#include "log.h" +#include "mg2d_boundary.h" +#include "mg2d_constants.h" +#include "ndarray.h" + +#define DOMAIN_SIZE 1.0 +#define FD_STENCIL 2 + +#if 1 +static double sol(double x, double y) +{ + return sin(M_PI * x) * sin(M_PI * y); +} +static double sol_dx(double x, double y) +{ + return M_PI * cos(M_PI * x) * sin(M_PI * y); +} +static double sol_dy(double x, double y) +{ + return M_PI * sin(M_PI * x) * cos(M_PI * y); +} +static double sol_dxx(double x, double y) +{ + return -M_PI * M_PI * sol(x, y); +} +static double sol_dyy(double x, double y) +{ + return -M_PI * M_PI * sol(x, y); +} +static double sol_dxy(double x, double y) +{ + return M_PI * M_PI * cos(M_PI * x) * cos(M_PI * y); +} +#endif + +int main(int argc, char **argv) +{ + EGSContext *ctx; + DomainGeometry *dg = NULL; + DomainComponent *dc = NULL; + long int log2N, log2maxiter; + long int N, maxiter; + double res_old, res_new; + int ret = 0; + + char processor_name[MPI_MAX_PROCESSOR_NAME]; + int nb_processes, rank, processor_name_len; + + if (argc < 3) { + fprintf(stderr, "Usage: %s \n", argv[0]); + return 1; + } + log2N = strtol(argv[1], NULL, 0); + log2maxiter = strtol(argv[2], NULL, 0); + if (log2N <= 0 || log2maxiter < 0 || + log2N >= sizeof(N) * 8 || log2maxiter >= sizeof(maxiter) * 8) { + fprintf(stderr, "Invalid log2N/log2maxiter values: %ld/%ld\n", + log2N, log2maxiter); + return 1; + } + + N = (1L << log2N) + 1; + maxiter = 1L << log2maxiter; + + MPI_Init(NULL, NULL); + + MPI_Comm_size(MPI_COMM_WORLD, &nb_processes); + MPI_Comm_rank(MPI_COMM_WORLD, &rank); + MPI_Get_processor_name(processor_name, &processor_name_len); + + fprintf(stderr, "This is process %d out of %d, running on %s\n", + rank, nb_processes, processor_name); + + dg = mg2di_dg_alloc(nb_processes); + if (!dg) { + fprintf(stderr, "Error allocating domain geometry\n"); + ret = 1; + goto fail; + } + + dg->domain_size[0] = N; + dg->domain_size[1] = N; + + for (unsigned int i = 0; i < dg->nb_components; i++) { + size_t patch_start, patch_end, patch_size_y; + + patch_size_y = (N + nb_processes - 1) / nb_processes; + patch_start = i * patch_size_y; + patch_end = MIN((i + 1) * patch_size_y, N); + patch_size_y = patch_end - patch_start; + if (patch_size_y <= 0) { + fprintf(stderr, "Too many processes for grid size %ld: %d\n", N, nb_processes); + ret = 1; + goto fail; + } + + dg->components[i].interior.start[0] = 0; + dg->components[i].interior.start[1] = patch_start; + dg->components[i].interior.size[0] = N; + dg->components[i].interior.size[1] = patch_size_y; + + dg->components[i].exterior.start[0] = -FD_STENCIL; + dg->components[i].exterior.start[1] = i ? patch_start : -FD_STENCIL; + dg->components[i].exterior.size[0] = N + 2 * FD_STENCIL; + dg->components[i].exterior.size[1] = patch_size_y + ((i == 0) * FD_STENCIL) + ((i == nb_processes - 1) * FD_STENCIL); + + dg->components[i].bnd_is_outer[MG2D_BOUNDARY_0L] = 1; + dg->components[i].bnd_is_outer[MG2D_BOUNDARY_0U] = 1; + dg->components[i].bnd_is_outer[MG2D_BOUNDARY_1L] = i == 0; + dg->components[i].bnd_is_outer[MG2D_BOUNDARY_1U] = i == nb_processes - 1; + } + dc = &dg->components[rank]; + + ctx = mg2di_egs_alloc_mpi(MPI_COMM_WORLD, dg); + if (!ctx) { + fprintf(stderr, "Error allocating the solver context\n"); + return 1; + } + + ctx->logger.log = mg2di_log_default_callback; + + ctx->step[0] = DOMAIN_SIZE / (N - 1.0); + ctx->step[1] = DOMAIN_SIZE / (N - 1.0); + + ctx->fd_stencil = FD_STENCIL; + + for (int bnd_loc = 0; bnd_loc < ARRAY_ELEMS(ctx->boundaries); bnd_loc++) { + MG2DBoundary *bnd = ctx->boundaries[bnd_loc]; + const int ci = mg2d_bnd_coord_idx(bnd_loc); + const int bnd_dir = mg2d_bnd_out_dir(bnd_loc); + + double coord[2]; + + if (!dc->bnd_is_outer[bnd_loc]) + continue; + + bnd->type = MG2D_BC_TYPE_FIXVAL; + + memset(bnd->val, 0, ctx->domain_size[!ci] * sizeof(*bnd->val)); + + for (int j = 1; j < ctx->fd_stencil; j++) { + double *dst = bnd->val + j * bnd->val_stride; + + coord[ci] = mg2d_bnd_is_upper(bnd_loc) * DOMAIN_SIZE + bnd_dir * j * ctx->step[ci]; + + for (ptrdiff_t k = -j; k < (ptrdiff_t)ctx->domain_size[!ci] + j; k++) { + coord[!ci] = (k + dc->interior.start[!ci]) * ctx->step[!ci]; + dst[k] = sol(coord[0], coord[1]); + } + } + } + + for (size_t y = 0; y < ctx->domain_size[1]; y++) { + const double y_coord = (y + dc->interior.start[1]) * ctx->step[1]; + + memset(NDPTR2D(ctx->u, 0, y), 0, sizeof(*ctx->u->data) * ctx->domain_size[0]); + + for (size_t x = 1; x < ctx->domain_size[0]; x++) { + const double x_coord = x * ctx->step[0]; + + *NDPTR2D(ctx->diff_coeffs[MG2D_DIFF_COEFF_02], x, y) = 1.0; + *NDPTR2D(ctx->diff_coeffs[MG2D_DIFF_COEFF_20], x, y) = 1.0; + *NDPTR2D(ctx->diff_coeffs[MG2D_DIFF_COEFF_11], x, y) = 1.0; + + *NDPTR2D(ctx->rhs, x, y) = sol_dxx(x_coord, y_coord) + sol_dyy(x_coord, y_coord) + sol_dxy(x_coord, y_coord); + } + + memset(NDPTR2D(ctx->diff_coeffs[MG2D_DIFF_COEFF_00], 0, y), 0, + sizeof(*ctx->diff_coeffs[0]->data) * ctx->domain_size[0]); + memset(NDPTR2D(ctx->diff_coeffs[MG2D_DIFF_COEFF_01], 0, y), 0, + sizeof(*ctx->diff_coeffs[0]->data) * ctx->domain_size[0]); + memset(NDPTR2D(ctx->diff_coeffs[MG2D_DIFF_COEFF_10], 0, y), 0, + sizeof(*ctx->diff_coeffs[0]->data) * ctx->domain_size[0]); + } + + ret = mg2di_egs_init(ctx, 0); + if (ret < 0) { + fprintf(stderr, "Error initializing the solver context: %d\n", ret); + ret = 1; + goto fail; + } + + MPI_Reduce(&ctx->residual_max, &res_old, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD); + + for (int i = 0; i < maxiter; i++) { + ret = mg2di_egs_solve(ctx, EGS_SOLVE_RELAXATION, 0); + if (ret < 0) { + fprintf(stderr, "Error during relaxation\n"); + ret = 1; + goto fail; + } + MPI_Reduce(&ctx->residual_max, &res_new, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD); + if (rank == 0) { + if (res_new > 1e3) { + fprintf(stderr, "Diverged at step %d: %g -> %g\n", i, res_old, res_new); + goto fail; + } + fprintf(stderr, "Step %d: %g -> %g (%g)\n", i, res_old, res_new, res_old / res_new); + res_old = res_new; + } + } + + { + double max_err = 0.0; + + for (size_t y = 0; y < ctx->domain_size[1]; y++) { + const double y_coord = (y + dc->interior.start[1]) * ctx->step[1]; + + for (size_t x = 0; x < ctx->domain_size[0]; x++) { + const double x_coord = x * ctx->step[0]; + double err = fabs(ctx->u->data[y * ctx->u->stride[0] + x] - sol(x_coord, y_coord)); + if (err > max_err) + max_err = err; + } + } + MPI_Reduce(rank ? &max_err : MPI_IN_PLACE, &max_err, 1, MPI_DOUBLE, MPI_MAX, 0, MPI_COMM_WORLD); + if (rank == 0) + fprintf(stderr, "max(|solution - exact|): %g\n", max_err); + } + +fail: + mg2di_egs_free(&ctx); + mg2di_dg_free(&dg); + MPI_Finalize(); + return ret; +} -- cgit v1.2.3