CODEWITHSUNDEEP
clinux
Siv
Siv

Reputation: 1

calculate program execution time in c and linux

In same program we can calculate function execution time but How to calculate other program (c program) execution time in another program . i tried using execve() and clock() and system() but i didn't get program execution time .

example :

#include<stdio.h>
#include<unistd.h>
#include<stdlib.h>
#include<signal.h>
#include<time.h>

main(int argc, char *argv[])
{

    pid_t child;
    pid_t tpid;

    int   status;
    char *envp[] = {NULL};
    char *newargv[] = {argv[1],argv[2],argv[3],NULL};
    clock_t start, end;
    double time_taken;

    child = fork();

    if(child == 0)
    {


        printf("in child\n");
        start = clock();
        execve(argv[1], newargv,envp);
        end = clock();
        time_taken = ((double)(end - start))/CLOCKS_PER_SEC;
            printf("fun() took %f seconds to execute \n", time_taken);

        exit(1);
    }

        if(child != 0) 
    {
        /* This is run by the parent.  Wait for the child
        to terminate. */
//  end  = clock();
//  time_taken = ((double)(end - start))/CLOCKS_PER_SEC;
//  printf("fun() took %f seconds to execute \n", time_taken);
    printf(" in parent\n");
        do {
        pid_t tpid;
    tpid = wait(&status);
//          if(tpid != child) process_terminated(tpid);
        }while(tpid != child);

         //return status;
    }
}

Upvotes: 0

Views: 1061

Answers (1)

Jean-Baptiste Yun&#232;s
Jean-Baptiste Yun&#232;s

Reputation: 36441

You can't use clock the way you did, because after having call exec your code is cleared so you can't get back into the original code. You can call clock before fork and then after wait in the parent but its a bad approximation of the child consumed time.

You have two basic functions to track time consumed by child processes:

clock_t times(struct tms *tp);

that gives you user and system time consumed by caller and children.

int getrusage(int who, struct rusage *r_usage);

that can let you choose who to track (self or children) and gives you many more finer informations about execution of tracked processes.

Just call one of these two after having wait for child(ren) to finish.

Upvotes: 1

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