Added a SPMD example.

examples/spmd/vector_scal.c

@@ -0,0 +1,142 @@
+/* StarPU --- Runtime system for heterogeneous multicore architectures.
+ *
+ * Copyright (C) 2010, 2011, 2012  Centre National de la Recherche Scientifique
+ * Copyright (C) 2010-2012  Université de Bordeaux 1
+ *
+ * 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.
+ */
+
+/* gcc build:
+
+   gcc -O2 -g vector_scal.c -o vector_scal $(pkg-config --cflags starpu-1.0) $(pkg-config --libs starpu-1.0)
+
+ */
+
+#include <starpu.h>
+#include <stdio.h>
+#include <limits.h>
+
+#define MIN(a,b)        ((a)<(b)?(a):(b))
+
+#define	NX	2048000
+#define FPRINTF(ofile, fmt, args ...) do { if (!getenv("STARPU_SSILENT")) {fprintf(ofile, fmt, ##args); }} while(0)
+
+static int get_first_element_rank(int nel, int rank, int nb_workers)
+{
+	if(rank == 0)
+		return 0;
+
+	/* We get the  number of bigger parts which stand before the part */
+	int nb_big_parts = MIN(nel % nb_workers, rank);
+
+	return nb_big_parts * (nel / nb_workers + 1) + (rank - nb_big_parts) * (nel / nb_workers);
+}
+
+void scal_cpu_func(void *buffers[], void *_args)
+{
+	unsigned i;
+	float *factor = _args, f = *factor;
+	struct starpu_vector_interface *vector = buffers[0];
+	unsigned n = STARPU_VECTOR_GET_NX(vector);
+	float *val = (float *)STARPU_VECTOR_GET_PTR(vector);
+
+	int nb_workers = starpu_combined_worker_get_size();
+	int rank = starpu_combined_worker_get_rank();
+
+	if (rank == 0)
+		FPRINTF(stderr, "running task with %d CPUs.\n", starpu_combined_worker_get_size());
+
+	/* We add 1 to the (nel_total % nb_workers) first workers, thus we get an evenly splitted data. */
+	int nel_worker = (n / nb_workers) + ((rank < (n % nb_workers)) ? 1 : 0);
+
+	int begin = get_first_element_rank(n, rank, nb_workers);
+
+
+	for (i = 0; i < nel_worker; i++) {
+		int rank = i + begin;
+
+		float v = val[rank];
+		int j;
+		for (j = 0; j < 100; j++)
+			v = v * f;
+		val[rank] = v;
+	}
+}
+
+static struct starpu_perfmodel vector_scal_model =
+{
+	.type = STARPU_HISTORY_BASED,
+	.symbol = "vector_scale_parallel"
+};
+
+static struct starpu_codelet cl =
+{
+	.modes = { STARPU_RW },
+	.where = STARPU_CPU,
+	.type = STARPU_SPMD,
+	.max_parallelism = INT_MAX,
+	.cpu_funcs = {scal_cpu_func, NULL},
+	.nbuffers = 1,
+	.model = &vector_scal_model,
+};
+
+int main(int argc, char **argv)
+{
+	struct starpu_conf conf;
+	float *vector;
+	unsigned i;
+	int ret;
+
+	vector = malloc(NX*sizeof(*vector));
+
+	for (i = 0; i < NX; i++)
+		vector[i] = (i+1.0f);
+
+	FPRINTF(stderr, "BEFORE: First element was %f\n", vector[0]);
+	FPRINTF(stderr, "BEFORE: Last element was %f\n", vector[NX-1]);
+
+	starpu_conf_init(&conf);
+
+	conf.single_combined_worker = 1;
+	conf.sched_policy_name = "pheft";
+
+	ret = starpu_init(&conf);
+	STARPU_CHECK_RETURN_VALUE(ret, "starpu_init");
+
+	starpu_data_handle_t vector_handle;
+	starpu_vector_data_register(&vector_handle, 0, (uintptr_t)vector, NX, sizeof(vector[0]));
+
+	float factor = 1.001;
+
+	for (i = 0; i < 100; i++) {
+		struct starpu_task *task = starpu_task_create();
+
+		task->cl = &cl;
+
+		task->handles[0] = vector_handle;
+		task->cl_arg = &factor;
+		task->cl_arg_size = sizeof(factor);
+
+		ret = starpu_task_submit(task);
+		STARPU_CHECK_RETURN_VALUE(ret, "starpu_task_submit");
+	}
+
+	starpu_data_unregister(vector_handle);
+
+	/* terminate StarPU, no task can be submitted after */
+	starpu_shutdown();
+
+	FPRINTF(stderr, "AFTER: First element is %f\n", vector[0]);
+	FPRINTF(stderr, "AFTER: Last element is %f\n", vector[NX-1]);
+
+	return 0;
+}