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export OMP_NUM_THREADS=8 gcc -o code18 code18.c -fopenmp ./code18
1 /*******************************************************************
2 * FILE: omp_hello.c
3 * DESCRIPTION:
4 * OpenMP Example - Hello World - C/C++ Version
5 * In this simple example, the master thread forks a parallel region.
6 * All threads in the team obtain their unique thread number and
7 * print it. The master thread only prints the total number of threads.
8 * Two OpenMP library routines are used to obtain the number of
9 * threads and each thread's number.
10 * AUTHOR: Blaise Barney 5/99
11 * LAST REVISED: 04/06/05
12 ******************************************************************* */
13 #include <omp.h>
14 #include <stdio.h>
15 #include <stdlib.h>
16
17 int main (int argc, char *argv[]) {
18
19 int nthreads, tid;
20 /* Fork a team of threads giving them their own copies of variables */
21 #pragma omp parallel private(nthreads, tid)
22 {
23 tid = omp_get_thread_num(); /* Obtain thread number */
24 printf("Hello World from thread : %d\n", tid);
25
26 /* Only master thread does this */
27 if (tid == 0)
28 {
29 nthreads = omp_get_num_threads();
30 printf("Number of threads = %d\n", nthreads);
31 }
32
33 } /* All threads join master thread and disband */
34 return 0;
35 }
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export OMP_NUM_THREADS=8 gcc -o code19 code19.c -fopenmp ./code19
1 #include <stdio.h>
2 #include <omp.h>
3 #include <unistd.h>
4
5 int a,b,x,y,num_threads,thread_num;
6 int main()
7 {
8 printf("I am in sequential part.\n");
9 #pragma omp parallel num_threads (8) private (a) shared (b)
10 {
11 num_threads=omp_get_num_threads();
12 thread_num=omp_get_thread_num();
13 x=thread_num;
14 //sleep(1);
15 y=x+1;
16 printf("I am openMP parellized part and thread %d. \n X and Y values are %d and %d. \n",omp_get_thread_num(),x,y);
17 }
18 printf("I am in sequential part again.\n");
19 return 0;
20 }
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gcc -o code20 code20.c -fopenmp ./code20
1 /*******************************************************************
2 * FILE: omp_workshare1.c
3 * DESCRIPTION:
4 * OpenMP Example - Loop Work-sharing - C/C++ Version
5 * In this example, the iterations of a loop are scheduled dynamically
6 * across the team of threads. A thread will perform CHUNK iterations
7 * at a time before being scheduled for the next CHUNK of work.
8 * AUTHOR: Blaise Barney 5/99
9 * LAST REVISED: 04/06/05
10 ******************************************************************* */
11 #include <omp.h>
12 #include <stdio.h>
13 #include <stdlib.h>
14 #define CHUNKSIZE 10
15 #define N 100
16
17 int main (int argc, char *argv[]) {
18
19 int nthreads, tid, i, chunk;
20 float a[N], b[N], c[N];
21
22 for (i=0; i < N; i++) /* Some initializations */
23 a[i] = b[i] = i * 1.0;
24 chunk = CHUNKSIZE;
25
26 #pragma omp parallel shared(a,b,c,nthreads,chunk) private(i,tid)
27 {
28 tid = omp_get_thread_num();
29 if (tid == 0) {
30 nthreads = omp_get_num_threads();
31 printf("Number of threads = %d\n", nthreads);
32 }
33 printf("Thread %d starting...\n",tid);
34
35 // #pragma omp for schedule(static,chunk)
36 #pragma omp for schedule(dynamic,chunk)
37 for (i=0; i<N; i++) {
38 c[i] = a[i] + b[i];
39 printf("Thread %d: c[%d]= %f\n",tid,i,c[i]);
40 }
41 } /* end of parallel section */
42 return 0;
43 }
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