starpu-max/mpi/examples/reduction/mpi_reduction.c

/* StarPU --- Runtime system for heterogeneous multicore architectures.
 *
 * Copyright (C) 2012  Centre National de la Recherche Scientifique
 *
 * StarPU is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation; either version 2.1 of the License, or (at
 * your option) any later version.
 *
 * StarPU is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * See the GNU Lesser General Public License in COPYING.LGPL for more details.
 */

#include <starpu_mpi.h>
#include <math.h>

#define X         5
#define Y         3

int display = 0;

extern void init_cpu_func(void *descr[], void *cl_arg);
extern void redux_cpu_func(void *descr[], void *cl_arg);
extern void dot_cpu_func(void *descr[], void *cl_arg);

static struct starpu_codelet init_codelet =
{
	.where = STARPU_CPU,
	.cpu_funcs = {init_cpu_func, NULL},
	.nbuffers = 1
};

static struct starpu_codelet redux_codelet =
{
	.where = STARPU_CPU,
	.cpu_funcs = {redux_cpu_func, NULL},
	.nbuffers = 2
};

static struct starpu_codelet dot_codelet =
{
	.where = STARPU_CPU,
	.cpu_funcs = {dot_cpu_func, NULL},
	.nbuffers = 3,
	.modes = {STARPU_R, STARPU_R, STARPU_REDUX}
};

static void parse_args(int argc, char **argv)
{
	int i;
	for (i = 1; i < argc; i++)
	{
		if (strcmp(argv[i], "-display") == 0)
		{
			display = 1;
		}
	}
}

/* Returns the MPI node number where data indexes index is */
int my_distrib(int x, int y, int nb_nodes)
{
	/* Block distrib */
	return ((int)(x / sqrt(nb_nodes) + (y / sqrt(nb_nodes)) * sqrt(nb_nodes))) % nb_nodes;
}

int main(int argc, char **argv)
{
        int my_rank, size, x, y;
        int value=0;
        unsigned matrixA[X][Y];
        unsigned matrixB[X][Y];
	unsigned dot, sum=0;
        starpu_data_handle_t handlesA[X][Y];
        starpu_data_handle_t handlesB[X][Y];
	starpu_data_handle_t dot_handle;

	starpu_init(NULL);
	starpu_mpi_initialize_extended(&my_rank, &size);
        parse_args(argc, argv);

        for(x = 0; x < X; x++)
	{
                for (y = 0; y < Y; y++)
		{
                        matrixA[x][y] = value;
                        matrixB[x][y] = 10+value;
                        value++;
                        sum += matrixA[x][y] + matrixB[x][y];
                }
        }

        for(x = 0; x < X; x++)
	{
                for (y = 0; y < Y; y++)
		{
                        int mpi_rank = my_distrib(x, y, size);
                        if (mpi_rank == my_rank)
			{
				/* Owning data */
				starpu_variable_data_register(&handlesA[x][y], 0, (uintptr_t)&(matrixA[x][y]), sizeof(unsigned));
				starpu_variable_data_register(&handlesB[x][y], 0, (uintptr_t)&(matrixB[x][y]), sizeof(unsigned));
			}
			else
			{
				starpu_variable_data_register(&handlesA[x][y], -1, (uintptr_t)NULL, sizeof(unsigned));
				starpu_variable_data_register(&handlesB[x][y], -1, (uintptr_t)NULL, sizeof(unsigned));
			}
			if (handlesA[x][y])
			{
                                starpu_data_set_rank(handlesA[x][y], mpi_rank);
                                starpu_data_set_tag(handlesA[x][y], (y*X)+x);
			}
			if (handlesB[x][y])
			{
                                starpu_data_set_rank(handlesB[x][y], mpi_rank);
                                starpu_data_set_tag(handlesB[x][y], (y*X)+x);
			}
		}
	}

	starpu_variable_data_register(&dot_handle, 0, (uintptr_t)&dot, sizeof(unsigned));
	starpu_data_set_rank(dot_handle, 0);
	starpu_data_set_reduction_methods(dot_handle, &redux_codelet, &init_codelet);

	for (x = 0; x < X; x++)
	{
		for (y = 0; y < Y ; y++)
		{
			starpu_mpi_insert_task(MPI_COMM_WORLD,
					       &dot_codelet,
					       STARPU_R, handlesA[x][y],
					       STARPU_R, handlesB[x][y],
					       STARPU_REDUX, dot_handle,
					       0);
		}
	}

        fprintf(stderr, "Waiting ...\n");
        starpu_task_wait_for_all();

        for(x = 0; x < X; x++)
	{
                for (y = 0; y < Y; y++)
		{
			if (handlesA[x][y]) starpu_data_unregister(handlesA[x][y]);
			if (handlesB[x][y]) starpu_data_unregister(handlesB[x][y]);
		}
	}
	if (dot_handle)
	{
		starpu_data_unregister(dot_handle);
	}

	starpu_mpi_shutdown();
	starpu_shutdown();

	if (display)
	{
                fprintf(stdout, "[%d] sum=%d\n", my_rank, sum);
                fprintf(stdout, "[%d] dot=%d\n", my_rank, dot);
        }

	return 0;
}