Using clock() to measure execution time

Question

I am running a C program using GCC and a proprietary DSP cross-compiler to simulate some functioality. I am using the following code to measure the execution time of particu

Answer 1

gettimeofday() function also can be considered.

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The gettimeofday() function shall obtain the current time, expressed as seconds and microseconds since the Epoch, and store it in the timeval structure pointed to by tp. The resolution of the system clock is unspecified.

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Calculating elapsed time in a C program in milliseconds

http://www.ccplusplus.com/2011/11/gettimeofday-example.html

Answer 2

clock measures the cpu time and not the wallclock time. Since you are not running the majority of your code on the cpu, this is not the right tool.

Answer 3

For durations like two hours, I wouldn't be too concerned about clock(), it's far more useful for measuring sub-second durations.

Just use time() if you want the actual elapsed time, something like (dummy stuff supplied for what was missing):

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

// Dummy stuff starts here
#include <unistd.h>
#define encoded 0
#define decoded 0
#define length 0
static void conv3_dec (int a, int b, int c, int d) {
    sleep (20);
}
// Dummy stuff ends here

int main (void) {
    time_t start, end, duration;
    puts ("DECODING DATA:");
    start = time (0);
    conv3_dec (encoded, decoded, 3 * length, 0);
    end = time (0);
    duration = end - start;
    printf ("DECODING TIME = %d\n", duration);
    return 0;
}

which generates:

DECODING DATA:
DECODING TIME = 20