OMP: Ejercicio semana 4

ejercicios/semana4-openmp/Makefile

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+CC=gcc
+CFLAGS=-g -ggdb -DPROFILE=3000 -Wall
+GLIB_FLAGS=`pkg-config --cflags --libs glib-2.0`
+
+all: tree tree_omp
+
+tree: tree.c
+	$(CC) -o tree $^ -lm -fopenmp $(CFLAGS) $(GLIB_FLAGS)
+
+tree_omp: tree_omp.c
+	$(CC) -o tree_omp $^ -lm -fopenmp $(CFLAGS) $(GLIB_FLAGS)
+
+.PHONY: clean
+clean:
+	rm -rf main *~ tree tree_omp

ejercicios/semana4-openmp/README.md

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+
+# Paralelización de construcción y recorrido de árboles
+
+Paraleliza las funciones `generate_nodes` y `sum` del programa `tree_omp.c`.
+Utiliza tareas de OpenMP para ello:
+
+ * Directiva #pragma omp task
+ * Utiliza el modificador if para limitar la cantidad de tareas que se generan.
+ * Directiva #pragma omp taskwait cuando sea necesario
+
+El programa utiliza la librería GLib para la estructura de datos GNode
+(árbol en memoria). La documentación está en https://developer.gnome.org/glib/2.26/glib-N-ary-Trees.html. Para instalar GLib hay que hacer:
+
+```
+sudo apt-get install libglib2.0-dev
+```
+
+Haz diversas pruebas variando la forma de utilizar tareas. Entrega el
+código desarrollado y una explicación breve de lo realizado, en
+particular discutiendo acerca del efecto de usar tareas para obtener
+mejores (o peores) tiempos de ejecución. No es necesario en este
+ejercicio realizar un informe detallado de las mejoras obtenidas.
+
+Nota: El programa `tree.c` es una versión que utiliza números
+aleatorios, pero no hay que paralelizarla.
+

ejercicios/semana4-openmp/tree.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+#include <string.h>
+#include <assert.h>
+#include <glib.h>
+
+#include <omp.h>
+
+#define MAX_HEIGHT 4
+#define MAX_CHILDREN 4
+#define FOLDER_RATIO 4 
+// 1/4 are folders => More folders may take more time
+
+#define DEBUG 0
+
+typedef struct {
+  char *name;
+  long size;
+  gboolean is_dir;
+} Item;
+
+char * new_name(int height, int child) {
+  char str[2048];
+  if (DEBUG)
+    printf("%d %d\n", height, child);
+  sprintf(str, "Node %d %d", height, child);
+  return g_strdup(str);
+}
+
+Item * item_new(char *name, long size, gboolean is_dir)
+{
+  Item *item = (Item *) malloc(sizeof(Item));
+  item->name = name;
+  item->size = size;
+  item->is_dir = is_dir;
+  return item;
+}
+
+void item_free(Item *item)
+{
+  free(item->name);
+  free(item);
+}
+
+void generate_nodes(GNode *root, int height) {
+  // https://developer.gnome.org/glib/stable/glib-N-ary-Trees.html
+
+  // Generate up to 30 children
+  int children = rand() % MAX_CHILDREN + 2;
+  for(int j = 0; j < children; j++) {
+    int size = 0;
+    int is_dir = (rand() % FOLDER_RATIO) == 0; // Some are folders
+    if (!is_dir) {
+      size = rand() % 500 + 20; 
+    }
+
+    GNode *node = g_node_new(item_new(new_name(height, j), size, is_dir));
+    g_node_append(root, node);
+
+    if (is_dir) {
+      // Decide whether to stop.
+      // Hard stop if the height is too much. If height is ok, we stop 1/4 of the times
+      if (height < MAX_HEIGHT && (rand() % 4) != 0) {
+	generate_nodes(node, height + 1);
+      }
+    }
+  }
+}
+
+long sum(GNode *root)
+{
+  long total = 0;
+  int nchildren = g_node_n_children(root);
+  for(int i = 0; i < nchildren; i++) {
+    GNode *child = g_node_nth_child(root, i);
+    Item *item = child->data;
+    if (item->is_dir) {
+      total += sum(child);
+    } else {
+      total += item->size;
+    }
+  }
+  return total;
+}
+
+
+void free_nodes(GNode *root) {
+  item_free(root->data);
+  int nchildren = g_node_n_children(root);
+  for(int i = 0; i < nchildren; i++) {
+    GNode *child = g_node_nth_child(root, i);
+    free_nodes(child);
+  }
+}
+
+void destroy_tree(GNode *root)
+{
+  free_nodes(root);
+  g_node_destroy(root);
+}
+
+int main(int argc, char **argv)
+{
+
+  GNode *root = g_node_new(item_new(new_name(0, 0), 0, TRUE));
+
+  double start = omp_get_wtime();
+  generate_nodes(root, 1);
+  double end = omp_get_wtime();
+  printf("Generation time %f seconds\n", end - start);
+
+  start = omp_get_wtime();
+  long total = sum(root);
+  end = omp_get_wtime();
+  printf("Total = %ld\n", total);
+  printf("Traversal time %f seconds\n", end - start);
+
+  destroy_tree(root);
+
+  return 0;  
+}

ejercicios/semana4-openmp/tree_omp.c

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+#include <stdio.h>
+#include <stdlib.h>
+
+#include <string.h>
+#include <assert.h>
+#include <glib.h>
+
+#include <omp.h>
+
+#define MAX_HEIGHT 15
+#define MAX_CHILDREN 12
+#define FOLDER_RATIO 4 
+// 1/4 are folders => More folders may take more time
+
+#define DEBUG 0
+
+typedef struct {
+  char *name;
+  long size;
+  gboolean is_dir;
+} Item;
+
+char * new_name(int height, int child) {
+  char str[2048];
+  if (DEBUG)
+    printf("%d %d\n", height, child);
+  sprintf(str, "Node %d %d", height, child);
+  return g_strdup(str);
+}
+
+Item * item_new(char *name, long size, gboolean is_dir)
+{
+  Item *item = (Item *) malloc(sizeof(Item));
+  item->name = name;
+  item->size = size;
+  item->is_dir = is_dir;
+  return item;
+}
+
+void item_free(Item *item)
+{
+  free(item->name);
+  free(item);
+}
+
+void generate_nodes(GNode *root, int height) {
+  // https://developer.gnome.org/glib/stable/glib-N-ary-Trees.html
+
+  // int children = rand() % MAX_CHILDREN + 2;
+  int children = MAX_CHILDREN;
+  for(int j = 0; j < children; j++) {
+    int size = 0;
+    int is_dir = j % FOLDER_RATIO == 0; //(rand() % FOLDER_RATIO) == 0; // Some are folders
+    if (!is_dir) {
+      //size = rand() % 500 + 20;
+      size = j + 10;
+    }
+
+    GNode *node = g_node_new(item_new(new_name(height, j), size, is_dir));
+    g_node_append(root, node);
+
+    if (is_dir) {
+      // Decide whether to stop.
+      // Hard stop if the height is too much. If height is ok, we stop 1/4 of the times
+      // if (height < MAX_HEIGHT && (rand() % 4) != 0) {
+      if (height < MAX_HEIGHT) {
+	generate_nodes(node, height + 1);
+      }
+    }
+  }
+}
+
+long sum(GNode *root, int height)
+{
+  long total = 0;
+  int nchildren = g_node_n_children(root);
+  for(int i = 0; i < nchildren; i++) {
+    GNode *child = g_node_nth_child(root, i);
+    Item *item = child->data;
+    if (item->is_dir) {
+      total += sum(child, height + 1);
+    } else {
+      total += item->size;
+    }
+  }
+  return total;
+}
+
+void free_nodes(GNode *root) {
+  item_free(root->data);
+  int nchildren = g_node_n_children(root);
+  for(int i = 0; i < nchildren; i++) {
+    GNode *child = g_node_nth_child(root, i);
+    free_nodes(child);
+  }
+}
+
+void destroy_tree(GNode *root)
+{
+  free_nodes(root);
+  g_node_destroy(root);
+}
+
+int main(int argc, char **argv)
+{
+
+  GNode *root = g_node_new(item_new(new_name(0, 0), 0, TRUE));
+
+  double start = omp_get_wtime();
+  generate_nodes(root, 1);
+  double end = omp_get_wtime();
+  printf("Generation time %f seconds\n", end - start);
+
+  long total;
+  start = omp_get_wtime();
+  total = sum(root, 1);
+  end = omp_get_wtime();
+  printf("Total = %ld\n", total);
+  printf("Traversal time %f seconds\n", end - start);
+
+  destroy_tree(root);
+
+  return 0;  
+}