elapsed time by jiffies

How to implement elapsed time by jiffies?




You can do something like this :

      struct timeval start, finish;
      long delta_usecs;

      do_gettimeofday(&start);
      ..
      // execute your processing here
      ..
      do_gettimeofday(&finish);

      delta_usecs = (finish.tv_sec - start.tv_sec) * 1000000 + (finish.tv_usec - start.tv_usec);






Since you are working on ARM arch, it may help to check the available resolution of your system timer by 
insmoding a kernel module that prints on dmesg the resolution:


#include <linux/version.h>
#include <linux/module.h>
#include <linux/hrtimer.h>
#include <linux/time.h>

static struct hrtimer timer;

static int __init hrtimer_test_init(void)
{
        struct timespec time;

        hrtimer_init(&timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS);
        hrtimer_get_res(CLOCK_MONOTONIC, &time);
        printk(KERN_ERR "resolution : %u secs and %u nsecs.\n", time.tv_sec, time.tv_nsec);
        return 0;
}

static void __exit hrtimer_test_exit(void)
{
        return ;
}

module_init(hrtimer_test_init);
module_exit(hrtimer_test_exit);
MODULE_LICENSE("GPL");