perf_examples/notify_group.c

/*
 * notify_group.c - self-sampling multuiple events in one group
 *
 * Copyright (c) 2009 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.
 */
#include <sys/types.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
#include <signal.h>
#include <fcntl.h>
#include <err.h>
#include <sys/prctl.h>
#include <sys/ioctl.h>
#include <sys/mman.h>

#include "perf_util.h"

#define SMPL_PERIOD	2400000000ULL

typedef struct {
	uint64_t	ip;
} sample_t;

static volatile unsigned long notification_received;

static perf_event_desc_t *fds;
static int num_fds;

static int buffer_pages = 1; /* size of buffer payload  (must be power of 2) */

static void
sigio_handler(int n, siginfo_t *info, struct sigcontext *sc)
{
	struct perf_event_header ehdr;
	uint64_t ip;
	int id, ret;
	
	id = perf_fd2event(fds, num_fds, info->si_fd);
	if (id == -1)
		errx(1, "cannot find event for descriptor %d", info->si_fd);

	ret = perf_read_buffer(fds+id, &ehdr, sizeof(ehdr));
	if (ret)
		errx(1, "cannot read event header");

	if (ehdr.type != PERF_RECORD_SAMPLE) {
		warnx("unknown event type %d, skipping", ehdr.type);
		perf_skip_buffer(fds+id, ehdr.size - sizeof(ehdr));
		goto skip;
	}

	ret = perf_read_buffer(fds+id, &ip, sizeof(ip));
	if (ret)
		errx(1, "cannot read IP");

	notification_received++;

	printf("Notification %lu: 0x%"PRIx64" fd=%d %s\n",
		notification_received,
		ip,
		info->si_fd, fds[id].name);

skip:
	/*
 	 * rearm the counter for one more shot
 	 */
	ret = ioctl(info->si_fd, PERF_EVENT_IOC_REFRESH, 1);
	if (ret == -1)
		err(1, "cannot refresh");

}

/*
 * infinite loop waiting for notification to get out
 */
void
busyloop(void)
{
	/*
	 * busy loop to burn CPU cycles
	 */
	for(;notification_received < 1024;) ;
}

int
main(int argc, char **argv)
{
	struct sigaction act;
	sigset_t new, old;
	size_t pgsz;
	int ret, i;

	ret = pfm_initialize();
	if (ret != PFM_SUCCESS)
		errx(1, "Cannot initialize library: %s", pfm_strerror(ret));

	pgsz = sysconf(_SC_PAGESIZE);

	/*
	 * Install the signal handler (SIGIO)
	 */
	memset(&act, 0, sizeof(act));
	act.sa_sigaction = (void (*)(int, siginfo_t *, void *)) sigio_handler;
	act.sa_flags = SA_SIGINFO;
	sigaction (SIGIO, &act, 0);

	sigemptyset(&old);
	sigemptyset(&new);
	sigaddset(&new, SIGIO);

	ret = sigprocmask(SIG_SETMASK, NULL, &old);
	if (ret)
		err(1, "sigprocmask failed");

	if (sigismember(&old, SIGIO)) {
		warnx("program started with SIGIO masked, unmasking it now\n");
		ret = sigprocmask(SIG_UNBLOCK, &new, NULL);
		if (ret)
			err(1, "sigprocmask failed");
	}

	/*
 	 * allocates fd for us
 	 */
	ret = perf_setup_list_events("cycles:u,"
				       "instructions:u,"
					"cycles:u",
				        &fds, &num_fds);
	if (ret || !num_fds)
		exit(1);

	fds[0].fd = -1;
	for(i=0; i < num_fds; i++) {
		/* want a notification for each sample added to the buffer */
		fds[i].hw.disabled =  !!i;
		printf("i=%d disabled=%d\n", i, fds[i].hw.disabled);
		fds[i].hw.wakeup_events = 1;
		fds[i].hw.sample_type = PERF_SAMPLE_IP;
		fds[i].hw.sample_period = SMPL_PERIOD;

		fds[i].fd = perf_event_open(&fds[i].hw, 0, -1, fds[0].fd, 0);
		if (fds[i].fd == -1) {
			warn("cannot attach event %s", fds[i].name);
			goto error;
		}

		fds[i].buf = mmap(NULL, (buffer_pages + 1)*pgsz, PROT_READ|PROT_WRITE, MAP_SHARED, fds[i].fd, 0);
		if (fds[i].buf == MAP_FAILED)
			err(1, "cannot mmap buffer");
		/*
		 * setup asynchronous notification on the file descriptor
		 */
		ret = fcntl(fds[i].fd, F_SETFL, fcntl(fds[i].fd, F_GETFL, 0) | O_ASYNC);
		if (ret == -1)
			err(1, "cannot set ASYNC");

		/*
		 * necessary if we want to get the file descriptor for
		 * which the SIGIO is sent for in siginfo->si_fd.
		 * SA_SIGINFO in itself is not enough
		 */
		ret = fcntl(fds[i].fd, F_SETSIG, SIGIO);
		if (ret == -1)
			err(1, "cannot setsig");

		/*
		 * get ownership of the descriptor
		 */
		ret = fcntl(fds[i].fd, F_SETOWN, getpid());
		if (ret == -1)
			err(1, "cannot setown");

		fds[i].pgmsk = (buffer_pages * pgsz) - 1;
	}

	for(i=0; i < num_fds; i++) {
		ret = ioctl(fds[i].fd, PERF_EVENT_IOC_REFRESH , 1);
		if (ret == -1)
			err(1, "cannot refresh");
	}

	busyloop();

	prctl(PR_TASK_PERF_EVENTS_DISABLE);

error:
	/*
	 * destroy our session
	 */
	for(i=0; i < num_fds; i++)
		if (fds[i].fd > -1)
			close(fds[i].fd);

	perf_free_fds(fds, num_fds);

	/* free libpfm resources cleanly */
	pfm_terminate();

	return 0;
}