aha/Documentation/perf_counter/builtin-record.c

#include "perf.h"
#include "builtin.h"
#include "util/util.h"
#include "util/parse-options.h"
#include "util/parse-events.h"

#include <sched.h>

#define ALIGN(x, a)		__ALIGN_MASK(x, (typeof(x))(a)-1)
#define __ALIGN_MASK(x, mask)	(((x)+(mask))&~(mask))

static int			default_interval = 100000;
static int			event_count[MAX_COUNTERS];

static int			fd[MAX_NR_CPUS][MAX_COUNTERS];
static int			nr_cpus				=  0;
static unsigned int		page_size;
static unsigned int		mmap_pages			= 16;
static int			output;
static const char		*output_name			= "output.perf";
static int			group				= 0;
static unsigned int		realtime_prio			= 0;
static int			system_wide			= 0;
static pid_t			target_pid			= -1;
static int			inherit				= 1;
static int			nmi				= 1;

const unsigned int default_count[] = {
	1000000,
	1000000,
	  10000,
	  10000,
	1000000,
	  10000,
};

struct mmap_data {
	int counter;
	void *base;
	unsigned int mask;
	unsigned int prev;
};

static unsigned int mmap_read_head(struct mmap_data *md)
{
	struct perf_counter_mmap_page *pc = md->base;
	int head;

	head = pc->data_head;
	rmb();

	return head;
}

static long events;
static struct timeval last_read, this_read;

static void mmap_read(struct mmap_data *md)
{
	unsigned int head = mmap_read_head(md);
	unsigned int old = md->prev;
	unsigned char *data = md->base + page_size;
	unsigned long size;
	void *buf;
	int diff;

	gettimeofday(&this_read, NULL);

	/*
	 * If we're further behind than half the buffer, there's a chance
	 * the writer will bite our tail and screw up the events under us.
	 *
	 * If we somehow ended up ahead of the head, we got messed up.
	 *
	 * In either case, truncate and restart at head.
	 */
	diff = head - old;
	if (diff > md->mask / 2 || diff < 0) {
		struct timeval iv;
		unsigned long msecs;

		timersub(&this_read, &last_read, &iv);
		msecs = iv.tv_sec*1000 + iv.tv_usec/1000;

		fprintf(stderr, "WARNING: failed to keep up with mmap data."
				"  Last read %lu msecs ago.\n", msecs);

		/*
		 * head points to a known good entry, start there.
		 */
		old = head;
	}

	last_read = this_read;

	if (old != head)
		events++;

	size = head - old;

	if ((old & md->mask) + size != (head & md->mask)) {
		buf = &data[old & md->mask];
		size = md->mask + 1 - (old & md->mask);
		old += size;
		while (size) {
			int ret = write(output, buf, size);
			if (ret < 0) {
				perror("failed to write");
				exit(-1);
			}
			size -= ret;
			buf += ret;
		}
	}

	buf = &data[old & md->mask];
	size = head - old;
	old += size;
	while (size) {
		int ret = write(output, buf, size);
		if (ret < 0) {
			perror("failed to write");
			exit(-1);
		}
		size -= ret;
		buf += ret;
	}

	md->prev = old;
}

static volatile int done = 0;

static void sig_handler(int sig)
{
	done = 1;
}

static struct pollfd event_array[MAX_NR_CPUS * MAX_COUNTERS];
static struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS];

static int nr_poll;
static int nr_cpu;

struct mmap_event {
	struct perf_event_header	header;
	__u32				pid;
	__u32				tid;
	__u64				start;
	__u64				len;
	__u64				pgoff;
	char				filename[PATH_MAX];
};

struct comm_event {
	struct perf_event_header	header;
	__u32				pid;
	__u32				tid;
	char				comm[16];
};

static pid_t pid_synthesize_comm_event(pid_t pid)
{
	struct comm_event comm_ev;
	char filename[PATH_MAX];
	pid_t spid, ppid;
	char bf[BUFSIZ];
	int fd, nr, ret;
	char comm[18];
	size_t size;
	char state;

	snprintf(filename, sizeof(filename), "/proc/%d/stat", pid);

	fd = open(filename, O_RDONLY);
	if (fd < 0) {
		fprintf(stderr, "couldn't open %s\n", filename);
		exit(EXIT_FAILURE);
	}
	if (read(fd, bf, sizeof(bf)) < 0) {
		fprintf(stderr, "couldn't read %s\n", filename);
		exit(EXIT_FAILURE);
	}
	close(fd);

	memset(&comm_ev, 0, sizeof(comm_ev));
        nr = sscanf(bf, "%d %s %c %d %d ",
			&spid, comm, &state, &ppid, &comm_ev.pid);
	if (nr != 5) {
		fprintf(stderr, "couldn't get COMM and pgid, malformed %s\n",
			filename);
		exit(EXIT_FAILURE);
	}
	comm_ev.header.type = PERF_EVENT_COMM;
	comm_ev.tid = pid;
	size = strlen(comm);
	comm[--size] = '\0'; /* Remove the ')' at the end */
	--size; /* Remove the '(' at the begin */
	memcpy(comm_ev.comm, comm + 1, size);
	size = ALIGN(size, sizeof(uint64_t));
	comm_ev.header.size = sizeof(comm_ev) - (sizeof(comm_ev.comm) - size);

	ret = write(output, &comm_ev, comm_ev.header.size);
	if (ret < 0) {
		perror("failed to write");
		exit(-1);
	}
	return comm_ev.pid;
}

static void pid_synthesize_mmap_events(pid_t pid, pid_t pgid)
{
	char filename[PATH_MAX];
	FILE *fp;

	snprintf(filename, sizeof(filename), "/proc/%d/maps", pid);

	fp = fopen(filename, "r");
	if (fp == NULL) {
		fprintf(stderr, "couldn't open %s\n", filename);
		exit(EXIT_FAILURE);
	}
	while (1) {
		char bf[BUFSIZ];
		unsigned char vm_read, vm_write, vm_exec, vm_mayshare;
		struct mmap_event mmap_ev = {
			.header.type = PERF_EVENT_MMAP,
		};
		unsigned long ino;
		int major, minor;
		size_t size;
		if (fgets(bf, sizeof(bf), fp) == NULL)
			break;

		/* 00400000-0040c000 r-xp 00000000 fd:01 41038  /bin/cat */
		sscanf(bf, "%llx-%llx %c%c%c%c %llx %x:%x %lu",
			&mmap_ev.start, &mmap_ev.len,
                        &vm_read, &vm_write, &vm_exec, &vm_mayshare,
                        &mmap_ev.pgoff, &major, &minor, &ino);
		if (vm_exec == 'x') {
			char *execname = strrchr(bf, ' ');

			if (execname == NULL || execname[1] != '/')
				continue;

			execname += 1;
			size = strlen(execname);
			execname[size - 1] = '\0'; /* Remove \n */
			memcpy(mmap_ev.filename, execname, size);
			size = ALIGN(size, sizeof(uint64_t));
			mmap_ev.len -= mmap_ev.start;
			mmap_ev.header.size = (sizeof(mmap_ev) -
					       (sizeof(mmap_ev.filename) - size));
			mmap_ev.pid = pgid;
			mmap_ev.tid = pid;

			if (write(output, &mmap_ev, mmap_ev.header.size) < 0) {
				perror("failed to write");
				exit(-1);
			}
		}
	}

	fclose(fp);
}

static void open_counters(int cpu, pid_t pid)
{
	struct perf_counter_hw_event hw_event;
	int counter, group_fd;
	int track = 1;

	if (pid > 0) {
		pid_t pgid = pid_synthesize_comm_event(pid);
		pid_synthesize_mmap_events(pid, pgid);
	}

	group_fd = -1;
	for (counter = 0; counter < nr_counters; counter++) {

		memset(&hw_event, 0, sizeof(hw_event));
		hw_event.config		= event_id[counter];
		hw_event.irq_period	= event_count[counter];
		hw_event.record_type	= PERF_RECORD_IP | PERF_RECORD_TID;
		hw_event.nmi		= nmi;
		hw_event.mmap		= track;
		hw_event.comm		= track;
		hw_event.inherit	= (cpu < 0) && inherit;

		track = 0; // only the first counter needs these

		fd[nr_cpu][counter] =
			sys_perf_counter_open(&hw_event, pid, cpu, group_fd, 0);

		if (fd[nr_cpu][counter] < 0) {
			int err = errno;
			printf("kerneltop error: syscall returned with %d (%s)\n",
					fd[nr_cpu][counter], strerror(err));
			if (err == EPERM)
				printf("Are you root?\n");
			exit(-1);
		}
		assert(fd[nr_cpu][counter] >= 0);
		fcntl(fd[nr_cpu][counter], F_SETFL, O_NONBLOCK);

		/*
		 * First counter acts as the group leader:
		 */
		if (group && group_fd == -1)
			group_fd = fd[nr_cpu][counter];

		event_array[nr_poll].fd = fd[nr_cpu][counter];
		event_array[nr_poll].events = POLLIN;
		nr_poll++;

		mmap_array[nr_cpu][counter].counter = counter;
		mmap_array[nr_cpu][counter].prev = 0;
		mmap_array[nr_cpu][counter].mask = mmap_pages*page_size - 1;
		mmap_array[nr_cpu][counter].base = mmap(NULL, (mmap_pages+1)*page_size,
				PROT_READ, MAP_SHARED, fd[nr_cpu][counter], 0);
		if (mmap_array[nr_cpu][counter].base == MAP_FAILED) {
			printf("kerneltop error: failed to mmap with %d (%s)\n",
					errno, strerror(errno));
			exit(-1);
		}
	}
	nr_cpu++;
}

static int __cmd_record(int argc, const char **argv)
{
	int i, counter;
	pid_t pid;
	int ret;

	page_size = sysconf(_SC_PAGE_SIZE);
	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
	assert(nr_cpus <= MAX_NR_CPUS);
	assert(nr_cpus >= 0);

	output = open(output_name, O_CREAT|O_RDWR, S_IRWXU);
	if (output < 0) {
		perror("failed to create output file");
		exit(-1);
	}

	if (!system_wide) {
		open_counters(-1, target_pid != -1 ? target_pid : 0);
	} else for (i = 0; i < nr_cpus; i++)
		open_counters(i, target_pid);

	signal(SIGCHLD, sig_handler);
	signal(SIGINT, sig_handler);

	if (target_pid == -1) {
		pid = fork();
		if (pid < 0)
			perror("failed to fork");

		if (!pid) {
			if (execvp(argv[0], (char **)argv)) {
				perror(argv[0]);
				exit(-1);
			}
		}
	}

	if (realtime_prio) {
		struct sched_param param;

		param.sched_priority = realtime_prio;
		if (sched_setscheduler(0, SCHED_FIFO, &param)) {
			printf("Could not set realtime priority.\n");
			exit(-1);
		}
	}

	/*
	 * TODO: store the current /proc/$/maps information somewhere
	 */

	while (!done) {
		int hits = events;

		for (i = 0; i < nr_cpu; i++) {
			for (counter = 0; counter < nr_counters; counter++)
				mmap_read(&mmap_array[i][counter]);
		}

		if (hits == events)
			ret = poll(event_array, nr_poll, 100);
	}

	return 0;
}

static const char * const record_usage[] = {
	"perf record [<options>] <command>",
	NULL
};

static char events_help_msg[EVENTS_HELP_MAX];

static const struct option options[] = {
	OPT_CALLBACK('e', "event", NULL, "event",
		     events_help_msg, parse_events),
	OPT_INTEGER('c', "count", &default_interval,
		    "event period to sample"),
	OPT_INTEGER('m', "mmap-pages", &mmap_pages,
		    "number of mmap data pages"),
	OPT_STRING('o', "output", &output_name, "file",
		    "output file name"),
	OPT_BOOLEAN('i', "inherit", &inherit,
		    "child tasks inherit counters"),
	OPT_INTEGER('p', "pid", &target_pid,
		    "record events on existing pid"),
	OPT_INTEGER('r', "realtime", &realtime_prio,
		    "collect data with this RT SCHED_FIFO priority"),
	OPT_BOOLEAN('a', "all-cpus", &system_wide,
			    "system-wide collection from all CPUs"),
	OPT_END()
};

int cmd_record(int argc, const char **argv, const char *prefix)
{
	int counter;

	create_events_help(events_help_msg);

	argc = parse_options(argc, argv, options, record_usage, 0);
	if (!argc)
		usage_with_options(record_usage, options);

	if (!nr_counters) {
		nr_counters = 1;
		event_id[0] = 0;
	}

	for (counter = 0; counter < nr_counters; counter++) {
		if (event_count[counter])
			continue;

		event_count[counter] = default_interval;
	}

	return __cmd_record(argc, argv);
}