/*

 * self-basic.c - example of a simple self monitoring task no-helper

 *

 * Copyright (c) 2010 Google, Inc

 * Contributed by Stephane Eranian <eranian@gmail.com>

 *

 * Permission is hereby granted, free of charge, to any person obtaining a copy

 * of this software and associated documentation files (the "Software"), to deal

 * in the Software without restriction, including without limitation the rights

 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies

 * of the Software, and to permit persons to whom the Software is furnished to do so,

 * subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in all

 * copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,

 * INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A

 * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT

 * HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF

 * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE

 * OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 *

 * This file is part of libpfm, a performance monitoring support library for

 * applications on Linux.

 */

#include <sys/types.h>

#include <inttypes.h>

#include <stdio.h>

#include <stdlib.h>

#include <stdarg.h>

#include <errno.h>

#include <unistd.h>

#include <string.h>

#include <locale.h>

#include <sys/ioctl.h>

#include <err.h>

#include <perfmon/pfmlib_perf_event.h>

#define N 30

static unsigned long 

fib(unsigned long n)

{

	if (n == 0)

		return 0;

	if (n == 1)

		return 2;

	return fib(n-1)+fib(n-2);

}

int

main(int argc, char **argv)

{

	struct perf_event_attr attr;

	int fd, ret;

	uint64_t count = 0, values[3];

	setlocale(LC_ALL, "");

	/*

	 * Initialize libpfm library (required before we can use it)

	 */

	ret = pfm_initialize();

	if (ret != PFM_SUCCESS)

		errx(1, "cannot initialize library: %s", pfm_strerror(ret));

	memset(&attr, 0, sizeof(attr));

	/*

 	 * 1st argument: event string

 	 * 2nd argument: default privilege level (used if not specified in the event string)

 	 * 3rd argument: the perf_event_attr to initialize

 	 */

	ret = pfm_get_perf_event_encoding("cycles", PFM_PLM0|PFM_PLM3, &attr, NULL, NULL);

	if (ret != PFM_SUCCESS)

		errx(1, "cannot find encoding: %s", pfm_strerror(ret));

	/*

	 * request timing information because event may be multiplexed

	 * and thus it may not count all the time. The scaling information

	 * will be used to scale the raw count as if the event had run all

	 * along

	 */

	attr.read_format = PERF_FORMAT_TOTAL_TIME_ENABLED|PERF_FORMAT_TOTAL_TIME_RUNNING;

	/* do not start immediately after perf_event_open() */

	attr.disabled = 1;

	/*

 	 * create the event and attach to self

 	 * Note that it attaches only to the main thread, there is no inheritance

 	 * to threads that may be created subsequently.

 	 *

 	 * if mulithreaded, then getpid() must be replaced by gettid()

 	 */

	fd = perf_event_open(&attr, getpid(), -1, -1, 0);

	if (fd < 0) 

		err(1, "cannot create event");

	/*

 	 * start counting now

 	 */

	ret = ioctl(fd, PERF_EVENT_IOC_ENABLE, 0);

	if (ret)

		err(1, "ioctl(enable) failed");

	printf("Fibonacci(%d)=%lu\n", N, fib(N));

	/*

 	 * stop counting

 	 */

	ret = ioctl(fd, PERF_EVENT_IOC_DISABLE, 0);

	if (ret)

		err(1, "ioctl(disable) failed");

	/*

 	 * read the count + scaling values

 	 *

 	 * It is not necessary to stop an event to read its value

 	 */

	ret = read(fd, values, sizeof(values));

	if (ret != sizeof(values))

		err(1, "cannot read results: %s", strerror(errno));

	/*

 	 * scale count

	 *

	 * values[0] = raw count

	 * values[1] = TIME_ENABLED

	 * values[2] = TIME_RUNNING

 	 */

	if (values[2])

		count = (uint64_t)((double)values[0] * values[1]/values[2]);

	printf("count=%'"PRIu64"\n", count);

	close(fd);

	/* free libpfm resources cleanly */

	pfm_terminate();

	return 0;

}