#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>

#define rdtsc(low,high) \
	__asm__ __volatile__("rdtsc" : "=a" (low), "=d" (high))

#define rdtscl(low) \
	__asm__ __volatile__("rdtsc" : "=a" (low) : : "edx")
 
/* p4 has a 512KB cache == 128 pages */
#define PAGE_SIZE	4096
#define CACHE_SIZE	(128 * PAGE_SIZE)
	
int main(int argc, char **argv)
{
	void *to, *from;
	void *cache_clear;
	unsigned long a, b;
	int i;

	cache_clear = mmap(NULL, CACHE_SIZE, PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
	to = mmap(NULL, 4096, PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
	from = mmap(NULL, 4096, PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);

	if (cache_clear == MAP_FAILED || to == MAP_FAILED || from == MAP_FAILED)
		exit(1);

	memset(to, PAGE_SIZE, 1);
	memset(from, PAGE_SIZE, 1);

	/* hit DCACHE with hammer */
	for (i = 0; i < 5; i++)
		memset(cache_clear, i, CACHE_SIZE); 
/*
	iopl(3);
	asm("cli");
*/	
	rdtscl(a);
	memcpy(to, from, PAGE_SIZE);
	rdtscl(b);
//	asm("sti");
	
	/* 
	 * never mind the high cycle count, we'll notice if it
	 * looks completely bogus 
	 */
	printf("took %lu cycles to copy a page\n", b - a);
	
	return 0;
}