From: VGoncalo <vitor.goncalo.costa@gmail.com>
Date: Wed, 25 Mar 2026 03:14:10 +0000 (+0000)
Subject: improving matrix init
X-Git-Url: https://vgcfreebox.myrthtech.pt/gitweb/ue-pp-squarematrixparallelisation.git/commitdiff_plain/03e6d97645ffb44eb652a00b7f87c327a855faaf?ds=sidebyside;hp=e1bc809d28992e9ab3b46078a6bd6de4618c1961

improving matrix init
---

diff --git a/ImprovedParallelMatricSearch.c b/ImprovedParallelMatricSearch.c
new file mode 100644
index 0000000..0df0ba1
--- /dev/null
+++ b/ImprovedParallelMatricSearch.c
@@ -0,0 +1,115 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <pthread.h>
+#include <time.h>
+
+const int m_rows = 40000;
+const int m_cols = 40000;
+const int threads_to_use = 8;
+
+_Atomic int hv = 0;
+int **matrix;
+
+typedef struct{
+  int start;
+  int end;
+} thread_args;
+
+void* parallel_search_cols(void *arg){
+  thread_args *args = (thread_args *)arg;
+  int local_hv = 0;
+  for(int r = 0; r < m_rows; r++){
+    for(int c = args->start; c < args->end; c++){
+      if(matrix[r][c] > local_hv){
+        local_hv = matrix[r][c];
+      }
+    }
+  }
+
+  if(local_hv > hv){
+    hv = local_hv;
+  }
+  return NULL;
+}
+
+void run_parallel_search(int num_threads) {
+    pthread_t *threads = malloc(num_threads * sizeof(pthread_t));
+    thread_args *args = malloc(num_threads * sizeof(thread_args));
+
+    if (threads == NULL || args == NULL) {
+        perror("Failed to allocate memory for threads");
+        exit(1);
+    }
+
+    int chunk_size = m_cols / num_threads;
+
+    for (int i = 0; i < num_threads; i++) {
+        args[i].start = i * chunk_size;
+        if (i == num_threads - 1) {
+            args[i].end = m_cols;
+        } else {
+            args[i].end = (i + 1) * chunk_size;
+        }
+        if (pthread_create(&threads[i], NULL, &parallel_search_cols, &args[i]) != 0) {
+            perror("Failed to create thread");
+            exit(1);
+        }
+    }
+
+    for (int i = 0; i < num_threads; i++) {
+        pthread_join(threads[i], NULL);
+    }
+    free(threads);
+    free(args);
+}
+
+void init_parallel_matrix(int num_threads){
+  for(int r = 0; r < m_rows; r++){  
+    for(int c = 0; c < m_cols; c++){
+      matrix[r][c] = r*m_cols+c;
+    }
+  }
+}
+
+int main(void){
+  printf("1st --> Allocate memory\n");
+  clock_t t_t1; t_t1 = clock();
+  size_t rows_size = m_rows * sizeof(int*);
+  matrix = malloc(rows_size);
+  if(matrix == NULL){
+    perror("malloc failled");
+    return 1;
+  }
+  size_t data_size = (size_t)m_rows * m_cols * sizeof(int);
+  int *data;
+  if(posix_memalign((void**)&data, 64, data_size) != 0){
+    perror("not able to alocate memory");
+    free(matrix);
+    return 1;
+  }
+  t_t1 = clock() - t_t1;
+  double t1_ttaken = ((double)t_t1)/CLOCKS_PER_SEC;
+  printf(" %f sec\n",t1_ttaken);
+
+  printf("2nd --> Populate the matrix\n");
+  clock_t t_t2; t_t2 = clock();
+  for(int r = 0; r<m_rows;r++){
+    matrix[r] = data + r * m_cols;
+  }
+  init_parallel_matrix(threads_to_use);
+  t_t2 = clock() - t_t2;
+  double t2_ttaken = ((double)t_t2)/CLOCKS_PER_SEC; 
+  printf(" %f sec\n",t2_ttaken);  
+  
+  printf("3rd --> Search matrix\n");
+  clock_t t_t3; t_t3 = clock();
+  run_parallel_search(threads_to_use);
+  t_t3 = clock() - t_t3;
+  double t3_ttaken = ((double)t_t3)/CLOCKS_PER_SEC;
+  printf(" %f sec\n",t3_ttaken);
+ 
+  printf("Done\n The biggest value found is  %d \n", hv); 
+  free(data);
+  free(matrix);
+  return 0;
+}
diff --git a/MatrixParallelPrograming.pdf b/MatrixParallelPrograming.pdf
index 14ce4f8..0ef406a 100644
Binary files a/MatrixParallelPrograming.pdf and b/MatrixParallelPrograming.pdf differ