/*
 * This little x86 app prints out the # of tight loops performed per sec,
 * averaged over 10 seconds.
 */
#include <stdlib.h>
#include <stdio.h>
#include <time.h>

#define rdtscll(val) \
     __asm__ __volatile__ ("rdtsc;" : "=A" (val))

#define SECS 10ULL

int main (int argc, char **argv)
{
	unsigned long long start, now, mhz, limit;
	unsigned int count;

	if (argc != 2) {
		printf("usage: loop_print <MHz>\n");
		exit(-1);
	}
	mhz = atol(argv[1]);
	limit = mhz * SECS;

repeat:
	rdtscll(start);
	count = 0;
	/*
	 * Just burn cycles in a tight, cached loop and measure absolute
	 * cycles elapsed, vs. loops performed:
	 */
	for (;;) {
		count++;
		rdtscll(now);
		if (now - start > limit)
			break;
	}
	printf("userspace speed: %d loops.\n", count/SECS); fflush(stdout);
	goto repeat;
}