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- #include <stdio.h>
- #include <time.h>
- #include <stdlib.h>
- #include <pthread.h>
- long int MAX;
- long int sum = 0;
- long int n_threads;
- pthread_mutex_t lock;
- void* somador(void *tid){
- long int i, start, end, sum_local = 0;
- long int *id = (long int *) tid;
- start = *id * (MAX / n_threads);
- if(*id == n_threads - 1)
- end = MAX;
- else
- end = start + (MAX / n_threads);
- for(i = start; i < end; i++)
- sum_local++;
- printf("thread %ld - sum = %ld\n", *id, sum_local);
- pthread_mutex_lock(&lock);
- sum += sum_local;
- pthread_mutex_unlock(&lock);
- pthread_exit(NULL);
- }
- int main(int argc, char ** argv) {
- if(argc != 3){
- fprintf(stderr, "Usage: %s <n_threads> <max>\n", argv[0]);
- exit(EXIT_FAILURE);
- }
- n_threads = atoi(argv[1]);
- MAX = atoi(argv[2]);
- long int tid;
- pthread_t *threads;
- struct timespec start, finish;
- double elapsed;
- threads = (pthread_t *) malloc(n_threads * sizeof(pthread_t));
- pthread_mutex_init(&lock, NULL);
- clock_gettime(CLOCK_MONOTONIC, &start);
- for(tid = 0; tid < n_threads; tid++)
- pthread_create(&threads[tid], NULL, (void *) somador, (void *) &tid);
- for(tid = 0; tid < n_threads; tid++)
- pthread_join(threads[tid], NULL);
- pthread_mutex_destroy(&lock);
- clock_gettime(CLOCK_MONOTONIC, &finish);
- elapsed = (finish.tv_sec - start.tv_sec) + (finish.tv_nsec - start.tv_nsec) / 1000000000.0;
- printf("\nTotal time: %.10f seconds\n\n", elapsed);
- printf("sum global = %ld\n", sum);
- free(threads);
- pthread_exit(NULL);
- }
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