#define rdtscll(val) \

__asm__ __volatile__ ("rdtsc" : "=A" (val))

#include<stdio.h>

int i;

unsigned long e;

#define as(p) \

__asm__ __volatile__ (p)

#define rdtscll() \

as("rdtsc")

int main(void)

{

	rdtscll();

	as("movl %eax,%ecx");

	rdtscll();

	as("subl %ecx,%eax");

	as("movl %eax,e");

	printf("duration:%lld\n", e);

	return 0;

}