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  1. #include <stdio.h>
  2. #include <stdlib.h>
  3. #include <pthread.h>
  4. #include <omp.h>
  5.  
  6. #define N 512  // Size of the matrix
  7. #define NUM_THREADS 4
  8.  
  9. // Global matrices
  10. int A[N][N], B[N][N], C[N][N];
  11.  
  12. // --- OpenMP Implementation ---
  13. void matrix_multiply_openmp(int A[N][N], int B[N][N], int C[N][N]) {
  14.     #pragma omp parallel for collapse(2)
  15.     for (int i = 0; i < N; i++) {
  16.         for (int j = 0; j < N; j++) {
  17.             C[i][j] = 0;
  18.             for (int k = 0; k < N; k++) {
  19.                 C[i][j] += A[i][k] * B[k][j];
  20.             }
  21.         }
  22.     }
  23. }
  24.  
  25. // --- POSIX Threads Implementation ---
  26. pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;
  27.  
  28. typedef struct {
  29.     int start_row, end_row;
  30. } ThreadData;
  31.  
  32. void *matrix_multiply_pthreads(void *arg) {
  33.     ThreadData *data = (ThreadData *)arg;
  34.     for (int i = data->start_row; i < data->end_row; i++) {
  35.         for (int j = 0; j < N; j++) {
  36.             C[i][j] = 0;
  37.             for (int k = 0; k < N; k++) {
  38.                 C[i][j] += A[i][k] * B[k][j];
  39.             }
  40.         }
  41.     }
  42.     return NULL;
  43. }
  44.  
  45. void matrix_multiply_pthreads_wrapper() {
  46.     pthread_t threads[NUM_THREADS];
  47.     ThreadData thread_data[NUM_THREADS];
  48.  
  49.     // Divide the matrix rows among threads
  50.     for (int i = 0; i < NUM_THREADS; i++) {
  51.         thread_data[i].start_row = i * (N / NUM_THREADS);
  52.         thread_data[i].end_row = (i + 1) * (N / NUM_THREADS);
  53.         pthread_create(&threads[i], NULL, matrix_multiply_pthreads, &thread_data[i]);
  54.     }
  55.  
  56.     // Join all threads
  57.     for (int i = 0; i < NUM_THREADS; i++) {
  58.         pthread_join(threads[i], NULL);
  59.     }
  60. }
  61.  
  62. // --- Main Function to Test All Implementations ---
  63. int main() {
  64.     // Initialize matrices A and B with some values (e.g., 1s)
  65.     for (int i = 0; i < N; i++) {
  66.         for (int j = 0; j < N; j++) {
  67.             A[i][j] = 1;
  68.             B[i][j] = 1;
  69.         }
  70.     }
  71.  
  72.     // OpenMP Matrix Multiplication
  73.     printf("Starting OpenMP Matrix Multiplication...\n");
  74.     matrix_multiply_openmp(A, B, C);
  75.     printf("OpenMP Matrix Multiplication Done!\n");
  76.  
  77.     // POSIX Threads Matrix Multiplication
  78.     printf("Starting POSIX Threads Matrix Multiplication...\n");
  79.     matrix_multiply_pthreads_wrapper();
  80.     printf("POSIX Threads Matrix Multiplication Done!\n");
  81.  
  82.     return 0;
  83. }
  84.  
Success #stdin #stdout 0.94s 5288KB
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stdin
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stdout
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Starting OpenMP Matrix Multiplication...
OpenMP Matrix Multiplication Done!
Starting POSIX Threads Matrix Multiplication...
POSIX Threads Matrix Multiplication Done!
https://ideone.com/JcizYH
language:
C (gcc 8.3)
created:
4 days ago
visibility:
public

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