ele709 lab 3.2, C (gcc)

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#include <stdio.h>
#include <time.h>
#include <stdlib.h>
#include <pthread.h>

struct thread_info {
   int maxitr;
   double exec_time;
};

typedef struct thread_info thread_info_t;

void *func(void *arg)
{
   struct timespec time_1, time_2;
   double exec_time;
   thread_info_t *info;
   int i, maxitr;
   volatile double a, b, c, count;

info = (thread_info_t *)arg;
   maxitr = info->maxitr;

b = 2.3; a = 4.5;

exec_time = 0.0;

clock_gettime(CLOCK_REALTIME, &time_1);
	if (count == 0){
   for (i = 0; i < maxitr ; i++) {
         c = a + b;
   } 
   count = 1;
   }
   elseif (count == 1) {
   for (i = 0; i < maxitr ; i++) {
         c = a - b;
   }
   count = 2;
   }
   elseif (count == 2) {
   for (i = 0; i < maxitr ; i++) {
         c = a * b;
   }
   count = 3;
   }
   elseif (count == 3){	    
   for (i = 0; i < maxitr ; i++) {
         c = a / b;
   }
   }
   else{
   		printf("A failure, your efforts notwithstanding.\n");
	}
    
	    printf("Computation: %lf\n", c);
   clock_gettime(CLOCK_REALTIME, &time_2);

exec_time = (time_2.tv_sec - time_1.tv_sec);
   exec_time = exec_time + (time_2.tv_nsec - time_1.tv_nsec)/1.0e9;

info->exec_time = exec_time;

pthread_exit(NULL);
   
}

int main(void)
{
   pthread_t thread1;
   thread_info_t info1;
   double maxitr;

maxitr = 5.0e8;

info1.maxitr = (int)maxitr;

if (pthread_create(&thread1, NULL, &func, &info1) != 0) {
           printf("Error in creating thread 1\n");
           exit(1);
   }

pthread_join(thread1, NULL);
   printf("Exec time for thread1 = %lf sec\n", info1.exec_time);

pthread_exit(NULL);
   main();
}

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Compilation time: 0.13 sec, absolute running time: 1.68 sec, cpu time: 2.1 sec, memory peak: 3 Mb, absolute service time: 1,82 sec