4.c

/*
============================================================================
Name : 4
Author : Piyush Singh
Description :   Write a program to measure how much time is taken to execute 100 getppid ( )
system call. Use time stamp counter.
Date: 18th Sep, 2025.
============================================================================
*/

#include <stdio.h>        // For printf()
#include <stdlib.h>       // For exit()
#include <sys/time.h>     // For gettimeofday(), struct timeval
#include <unistd.h>       // For getppid()

int main() 
{
    struct timeval start, end;
    long elapsed;

    // Step 1: Record start time
    if (gettimeofday(&start, NULL) == -1) 
    {
        perror("❌ gettimeofday (start) failed");
        exit(1);
    }

    // Step 2: Call getppid() 100 times
    for (int i = 0; i < 100; i++) 
        getppid();  // System call to get parent process ID

    // Step 3: Record end time
    if (gettimeofday(&end, NULL) == -1) 
    {
        perror("❌ gettimeofday (end) failed");
        exit(1);
    }

    // Step 4: Calculate elapsed time in microseconds
    elapsed = (end.tv_sec - start.tv_sec) * 1000000L +
              (end.tv_usec - start.tv_usec);

    // Step 5: Display result
    printf("⏱️ Time taken for 100 getppid() calls: %ld microseconds\n", elapsed);

    return 0;
}

/*
Output :
./4                                                                        ─╯
⏱️ Time taken for 100 getppid() calls: 23 microseconds
*/