clock_getime()

[TiredStudent]

Hi.

I am working on a project for a multi-threaded prime number generator. All is working good except for one piece. I need to get the time for my program to generate my prime list. It is suggested in the assignment to use clock_gettime. But all I get is zeros when I get the values stored in the timespec struct. Any hints as to which clock_id I should be using? CLOCK_REALTIME is the only one so far that the compiler doesn't have a hissy fit over.

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

#include <sys/time.h>
   void *primeGenerator();
	float calcTime(struct timespec *,struct timespec *);
	
   int highestChecked;
   int maxNum;

   int main(int arg, char *argv[])
   {
      int i;
      highestChecked=0;
      while(1)
      {
         if(argv[1]==NULL)
         {
            printf("Invalid parameters.\n");
            exit(1);
         }
         if(argv[2]==NULL)
         {
            printf("Invalid parameters.\n");
            exit(1);
         }
         else
         {
	     struct timespec init;
		int time = clock_gettime(CLOCK_REALTIME, &init);
		if(time !=0) printf("Time Calculation Bad. Error in call to gettime\n");
            maxNum = atoi(argv[1]);
            printf("Max number: %d\n", maxNum);			
            int numThreads = atoi(argv[2]);
            printf("Numthreads %d\n",numThreads);		
            pthread_t tid[numThreads];
            pthread_attr_t attr;
         
            pthread_attr_init(&attr);
         
         //Creates the numThreads threads
            for(i=0; i<numThreads; i++) pthread_create(&tid[i],&attr,primeGenerator, NULL);
         
         //Join the threads
            for(i=0; i<numThreads; i++) pthread_join(tid[i], NULL);
         
			
				struct timespec final;
				time = clock_gettime(CLOCK_REALTIME, &final);
				if(time !=0) printf("Time Calculation Bad. Error in call to gettime\n");			
			
				fprintf(stderr, "%d,%d\n", maxNum, numThreads);
				
				//Testers
				printf("Sec:				%f\n", init.tv_sec);
				printf("NanSec:			%lf\n", init.tv_nsec);
				printf("End Sec:			%f\n", final.tv_sec);
				printf("End NanSec:		%f\n", init.tv_nsec);
				
				
            break;
         }
      }
      return 0;
   }

I get all zeros in all cases from the ending print statements.

Any hints would appreciated.
Thanks.

[quzah]

You are including time.h which defines something called time. So you shouldn't reuse that word for your variable name:

int time = clock_gettime(CLOCK_REALTIME, &init);

If you run just a small program that checks time, does it work there?

#include<stdio.h>
#include <time.h> 
#include <sys/time.h>
int main( void )
{
    struct timespec init;
    int t = clock_gettime(CLOCK_REALTIME, &init);
    printf( "init.tv_sec: %d\n", init.tv_sec );
    printf( "init.tv_nsec: %d\n", init.tv_nsec );

    return 0;
}

Do you get the same thing for each clock type?


Quzah.

[TiredStudent]

Ok. Got it fixed! Thanks for pointing out the time name issue; I hadn't realized I did that. The problem was in my print statements. I was using %f or %lf think of printing it as a float, changing it to %d gave me the times it was storing. Your example for the small program lead me to that. You saved me a lot of frustration! One day I'll learn the problem is never where I am so sure it is.

Thanks,
~TS

[quzah]

You should turn up the warning levels on your compiler, it will help catch things like that.


Quzah.