#include <tools.h>
#include <unistd.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/mman.h>
#include <sys/sysctl.h>

char *file = "/dev/ad0"; int fd;
off_t size = (off_t) 19*G;
#define NOW (rdtsc()/550)
#define F_PURGE 42

int main(int argc, char *argv[])
{
	off_t pos, leap;
	int iter;
	char buf[64*K];
	long long before, after;

	fd = open(file, O_RDONLY);
	unless (fd >= 0) pdie("open");
	srandom(time(0)+getpid());

	for (leap = 512; leap < 20*((off_t) G); leap = (off_t)(leap * 1.1)) {
		long long tot = 0;
		/* fcntl(fd, F_PURGE); */
		for (iter = 0; iter < 50; iter++) {
			pos = (random() % ((size - leap) >> Mshift)) << Mshift;
			pos |= (random() % M);

			if (lseek(fd, pos, SEEK_SET) < 0) pdie("lseek");
			if (read(fd, buf, 512) < 0) pdie("read");

			pos += leap;

			if (lseek(fd, pos, SEEK_SET) < 0) pdie("lseek");
			before = NOW;
			if (read(fd, buf, 512) < 0) pdie("read");
			after = NOW;

			/* printf("%lld\t%g\n", leap/512, (after-before)/1000.0); */
			tot += after - before;
		}
		printf("%lld\t%g\n", leap/512, (tot/1000.0)/iter);
		fflush(stdout);
	}

	return 0;
}