Documentation/perf_counter/kerneltop.c

/*
 * kerneltop.c: show top kernel functions - performance counters showcase

   Build with:

     cc -O6 -Wall `pkg-config --cflags --libs glib-2.0` -o kerneltop kerneltop.c

   Sample output:

------------------------------------------------------------------------------
 KernelTop:    2669 irqs/sec  [NMI, cache-misses/cache-refs],  (all, cpu: 2)
------------------------------------------------------------------------------

             weight         RIP          kernel function
             ______   ________________   _______________

              35.20 - ffffffff804ce74b : skb_copy_and_csum_dev
              33.00 - ffffffff804cb740 : sock_alloc_send_skb
              31.26 - ffffffff804ce808 : skb_push
              22.43 - ffffffff80510004 : tcp_established_options
              19.00 - ffffffff8027d250 : find_get_page
              15.76 - ffffffff804e4fc9 : eth_type_trans
              15.20 - ffffffff804d8baa : dst_release
              14.86 - ffffffff804cf5d8 : skb_release_head_state
              14.00 - ffffffff802217d5 : read_hpet
              12.00 - ffffffff804ffb7f : __ip_local_out
              11.97 - ffffffff804fc0c8 : ip_local_deliver_finish
               8.54 - ffffffff805001a3 : ip_queue_xmit

  Started by Ingo Molnar <mingo@redhat.com>

  Improvements and fixes by:

    Arjan van de Ven <arjan@linux.intel.com>
    Yanmin Zhang <yanmin.zhang@intel.com>
    Mike Galbraith <efault@gmx.de>

  Released under the GPL v2. (and only v2, not any later version)

 */
#define _GNU_SOURCE
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdint.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <time.h>

#include <glib.h>

#include <sys/syscall.h>
#include <sys/ioctl.h>
#include <sys/poll.h>
#include <sys/prctl.h>
#include <sys/wait.h>
#include <sys/uio.h>

#include <linux/unistd.h>

#ifdef __x86_64__
# define __NR_perf_counter_open	295
#endif

#ifdef __i386__
# define __NR_perf_counter_open 333
#endif

/*
 * Pick up some kernel type conventions:
 */
#define __user
#define asmlinkage

typedef unsigned int		__u32;
typedef unsigned long long	__u64;
typedef long long		__s64;

/*
 * User-space ABI bits:
 */

/*
 * Generalized performance counter event types, used by the hw_event.type
 * parameter of the sys_perf_counter_open() syscall:
 */
enum hw_event_types {
	/*
	 * Common hardware events, generalized by the kernel:
	 */
	PERF_COUNT_CPU_CYCLES		=  0,
	PERF_COUNT_INSTRUCTIONS		=  1,
	PERF_COUNT_CACHE_REFERENCES	=  2,
	PERF_COUNT_CACHE_MISSES		=  3,
	PERF_COUNT_BRANCH_INSTRUCTIONS	=  4,
	PERF_COUNT_BRANCH_MISSES	=  5,
	PERF_COUNT_BUS_CYCLES		=  6,

	PERF_HW_EVENTS_MAX		=  7,

	/*
	 * Special "software" counters provided by the kernel, even if
	 * the hardware does not support performance counters. These
	 * counters measure various physical and sw events of the
	 * kernel (and allow the profiling of them as well):
	 */
	PERF_COUNT_CPU_CLOCK		= -1,
	PERF_COUNT_TASK_CLOCK		= -2,
	PERF_COUNT_PAGE_FAULTS		= -3,
	PERF_COUNT_CONTEXT_SWITCHES	= -4,
	PERF_COUNT_CPU_MIGRATIONS	= -5,

	PERF_SW_EVENTS_MIN		= -6,
};

/*
 * IRQ-notification data record type:
 */
enum perf_counter_record_type {
	PERF_RECORD_SIMPLE		=  0,
	PERF_RECORD_IRQ			=  1,
	PERF_RECORD_GROUP		=  2,
};

/*
 * Hardware event to monitor via a performance monitoring counter:
 */
struct perf_counter_hw_event {
	__s64			type;

	__u64			irq_period;
	__u64			record_type;
	__u64			read_format;

	__u64			disabled       :  1, /* off by default        */
				nmi	       :  1, /* NMI sampling          */
				raw	       :  1, /* raw event type        */
				inherit	       :  1, /* children inherit it   */
				pinned	       :  1, /* must always be on PMU */
				exclusive      :  1, /* only group on PMU     */
				exclude_user   :  1, /* don't count user      */
				exclude_kernel :  1, /* ditto kernel          */
				exclude_hv     :  1, /* ditto hypervisor      */
				exclude_idle   :  1, /* don't count when idle */

				__reserved_1   : 54;

	__u32			extra_config_len;
	__u32			__reserved_4;

	__u64			__reserved_2;
	__u64			__reserved_3;
};

/*
 * Ioctls that can be done on a perf counter fd:
 */
#define PERF_COUNTER_IOC_ENABLE		_IO('$', 0)
#define PERF_COUNTER_IOC_DISABLE	_IO('$', 1)

asmlinkage int sys_perf_counter_open(

	struct perf_counter_hw_event	*hw_event_uptr		__user,
	pid_t				pid,
	int				cpu,
	int				group_fd,
	unsigned long			flags)
{
	int ret;

	ret = syscall(
		__NR_perf_counter_open, hw_event_uptr, pid, cpu, group_fd, flags);
#if defined(__x86_64__) || defined(__i386__)
	if (ret < 0 && ret > -4096) {
		errno = -ret;
		ret = -1;
	}
#endif
	return ret;
}

const char *event_types [] = {
	"CPU cycles",
	"instructions",
	"cache-refs",
	"cache-misses",
	"branches",
	"branch-misses",
	"bus cycles"
};

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

/*
 * prctl(PR_TASK_PERF_COUNTERS_DISABLE) will (cheaply) disable all
 * counters in the current task.
 */
#define PR_TASK_PERF_COUNTERS_DISABLE           31
#define PR_TASK_PERF_COUNTERS_ENABLE            32

#define MAX_COUNTERS		8

static int			nr_counters			= -1;

static __u64			count_filter		       = 100;

#define MAX_NR_CPUS		256

static int			event_count[MAX_COUNTERS];
static unsigned long		event_id[MAX_COUNTERS];
static int			event_raw[MAX_COUNTERS];

static int			tid				= -1;
static int			profile_cpu			= -1;
static int			nr_cpus				=  0;
static int			nmi				=  1;
static int			group				=  0;

static char			*vmlinux;

static char			*sym_filter;
static unsigned long		filter_start;
static unsigned long		filter_end;

static int			delay_secs			=  2;
static int			zero;
static int			dump_symtab;

struct source_line {
	uint64_t		EIP;
	unsigned long		count;
	char			*line;
};

static GList			*lines;

static void display_help(void)
{
	printf(
	"Usage: kerneltop [<options>]\n\n"
	"KernelTop Options (up to %d event types can be specified at once):\n\n",
		 MAX_COUNTERS);
	printf(
	" -e EID    --event_id=EID     # event type ID                    [default:  0]\n"
	"                                   0: CPU cycles\n"
	"                                   1: instructions\n"
	"                                   2: cache accesses\n"
	"                                   3: cache misses\n"
	"                                   4: branch instructions\n"
	"                                   5: branch prediction misses\n"
	"                                   6: bus cycles\n\n"
	"                                rNNN: raw PMU events (eventsel+umask)\n\n"
	" -c CNT    --count=CNT        # event period to sample\n\n"
	" -C CPU    --cpu=CPU          # CPU (-1 for all)                 [default: -1]\n"
	" -p PID    --pid=PID          # PID of sampled task (-1 for all) [default: -1]\n\n"
	" -d delay  --delay=<seconds>  # sampling/display delay           [default:  2]\n"
	" -f CNT --filter=CNT          # min-event-count filter          [default: 100]\n\n"
	" -s symbol --symbol=<symbol>  # function to be showed annotated one-shot\n"
	" -x path   --vmlinux=<path>   # the vmlinux binary, required for -s use:\n"
	" -z        --zero             # zero counts after display\n"
	" -D        --dump_symtab      # dump symbol table to stderr on startup\n"
	"\n");

	exit(0);
}

static void process_options(int argc, char *argv[])
{
	int error = 0, counter;

	for (;;) {
		int option_index = 0;
		/** Options for getopt */
		static struct option long_options[] = {
			{"count",	required_argument,	NULL, 'c'},
			{"cpu",		required_argument,	NULL, 'C'},
			{"delay",	required_argument,	NULL, 'd'},
			{"dump_symtab",	no_argument,		NULL, 'D'},
			{"event_id",	required_argument,	NULL, 'e'},
			{"filter",	required_argument,	NULL, 'f'},
			{"group",	required_argument,	NULL, 'g'},
			{"help",	no_argument,		NULL, 'h'},
			{"nmi",		required_argument,	NULL, 'n'},
			{"pid",		required_argument,	NULL, 'p'},
			{"vmlinux",	required_argument,	NULL, 'x'},
			{"symbol",	required_argument,	NULL, 's'},
			{"zero",	no_argument,		NULL, 'z'},
			{NULL,		0,			NULL,  0 }
		};
		int c = getopt_long(argc, argv, "c:C:d:De:f:g:hn:p:s:x:z",
				    long_options, &option_index);
		if (c == -1)
			break;

		switch (c) {
		case 'c':
			if (nr_counters == -1)
				nr_counters = 0;
			event_count[nr_counters]	=   atoi(optarg); break;
		case 'C':
			/* CPU and PID are mutually exclusive */
			if (tid != -1) {
				printf("WARNING: CPU switch overriding PID\n");
				sleep(1);
				tid = -1;
			}
			profile_cpu			=   atoi(optarg); break;
		case 'd': delay_secs			=   atoi(optarg); break;
		case 'D': dump_symtab			=              1; break;

		case 'e':
			nr_counters++;
			if (nr_counters == MAX_COUNTERS) {
				error = 1;
				break;
			}
			if (*optarg == 'r') {
				event_raw[nr_counters] = 1;
				++optarg;
			}
			event_id[nr_counters] = strtol(optarg, NULL, 16);
			break;

		case 'f': count_filter			=   atoi(optarg); break;
		case 'g': group				=   atoi(optarg); break;
		case 'h':      				  display_help(); break;
		case 'n': nmi				=   atoi(optarg); break;
		case 'p':
			/* CPU and PID are mutually exclusive */
			if (profile_cpu != -1) {
				printf("WARNING: PID switch overriding CPU\n");
				sleep(1);
				profile_cpu = -1;
			}
			tid				=   atoi(optarg); break;
		case 's': sym_filter			= strdup(optarg); break;
		case 'x': vmlinux			= strdup(optarg); break;
		case 'z': zero				=              1; break;
		default: error = 1; break;
		}
	}
	if (error)
		display_help();

	nr_counters++;
	if (nr_counters < 1)
		nr_counters = 1;

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

		if (event_id[counter] < PERF_HW_EVENTS_MAX)
			event_count[counter] = default_count[event_id[counter]];
		else
			event_count[counter] = 100000;
	}
}

static uint64_t			min_ip;
static uint64_t			max_ip = -1ll;

struct sym_entry {
	unsigned long long	addr;
	char			*sym;
	unsigned long		count[MAX_COUNTERS];
	int			skip;
	GList			*source;
};

#define MAX_SYMS		100000

static int sym_table_count;

struct sym_entry		*sym_filter_entry;

static struct sym_entry		sym_table[MAX_SYMS];

static void show_details(struct sym_entry *sym);

/*
 * Ordering weight: count-1 * count-1 * ... / count-n
 */
static double sym_weight(const struct sym_entry *sym)
{
	double weight;
	int counter;

	weight = sym->count[0];

	for (counter = 1; counter < nr_counters-1; counter++)
		weight *= sym->count[counter];

	weight /= (sym->count[counter] + 1);

	return weight;
}

static int compare(const void *__sym1, const void *__sym2)
{
	const struct sym_entry *sym1 = __sym1, *sym2 = __sym2;

	return sym_weight(sym1) < sym_weight(sym2);
}

static time_t			last_refresh;
static long			events;
static long			userspace_events;
static const char		CONSOLE_CLEAR[] = "";

static struct sym_entry		tmp[MAX_SYMS];

static void print_sym_table(void)
{
	int i, printed;
	int counter;
	float events_per_sec = events/delay_secs;
	float kevents_per_sec = (events-userspace_events)/delay_secs;

	memcpy(tmp, sym_table, sizeof(sym_table[0])*sym_table_count);
	qsort(tmp, sym_table_count, sizeof(tmp[0]), compare);

	write(1, CONSOLE_CLEAR, strlen(CONSOLE_CLEAR));

	printf(
"------------------------------------------------------------------------------\n");
	printf( " KernelTop:%8.0f irqs/sec  kernel:%3.1f%% [%s, ",
		events_per_sec,
		100.0 - (100.0*((events_per_sec-kevents_per_sec)/events_per_sec)),
		nmi ? "NMI" : "IRQ");

	if (nr_counters == 1)
		printf("%d ", event_count[0]);

	for (counter = 0; counter < nr_counters; counter++) {
		if (counter)
			printf("/");

		if (event_id[counter] < PERF_HW_EVENTS_MAX)
			printf( "%s", event_types[event_id[counter]]);
		else
			printf( "raw:%04lx", event_id[counter]);
	}

	printf( "], ");

	if (tid != -1)
		printf(" (tid: %d", tid);
	else
		printf(" (all");

	if (profile_cpu != -1)
		printf(", cpu: %d)\n", profile_cpu);
	else {
		if (tid != -1)
			printf(")\n");
		else
			printf(", %d CPUs)\n", nr_cpus);
	}

	printf("------------------------------------------------------------------------------\n\n");

	if (nr_counters == 1)
		printf("             events");
	else
		printf("  weight     events");

	printf("         RIP          kernel function\n"
	       	       "  ______     ______   ________________   _______________\n\n"
	);

	printed = 0;
	for (i = 0; i < sym_table_count; i++) {
		int count;

		if (nr_counters == 1) {
			if (printed <= 18 &&
					tmp[i].count[0] >= count_filter) {
				printf("%19.2f - %016llx : %s\n",
				  sym_weight(tmp + i), tmp[i].addr, tmp[i].sym);
				printed++;
			}
		} else {
			if (printed <= 18 &&
					tmp[i].count[0] >= count_filter) {
				printf("%8.1f %10ld - %016llx : %s\n",
				  sym_weight(tmp + i),
				  tmp[i].count[0],
				  tmp[i].addr, tmp[i].sym);
				printed++;
			}
		}
		/*
		 * Add decay to the counts:
		 */
		for (count = 0; count < nr_counters; count++)
			sym_table[i].count[count] = zero ? 0 : sym_table[i].count[count] * 7 / 8;
	}

	if (sym_filter_entry)
		show_details(sym_filter_entry);

	last_refresh = time(NULL);

	{
		struct pollfd stdin_poll = { .fd = 0, .events = POLLIN };

		if (poll(&stdin_poll, 1, 0) == 1) {
			printf("key pressed - exiting.\n");
			exit(0);
		}
	}
}

static int read_symbol(FILE *in, struct sym_entry *s)
{
	static int filter_match = 0;
	char *sym, stype;
	char str[500];
	int rc, pos;

	rc = fscanf(in, "%llx %c %499s", &s->addr, &stype, str);
	if (rc == EOF)
		return -1;

	assert(rc == 3);

	/* skip until end of line: */
	pos = strlen(str);
	do {
		rc = fgetc(in);
		if (rc == '\n' || rc == EOF || pos >= 499)
			break;
		str[pos] = rc;
		pos++;
	} while (1);
	str[pos] = 0;

	sym = str;

	/* Filter out known duplicates and non-text symbols. */
	if (!strcmp(sym, "_text"))
		return 1;
	if (!min_ip && !strcmp(sym, "_stext"))
		return 1;
	if (!strcmp(sym, "_etext") || !strcmp(sym, "_sinittext"))
		return 1;
	if (stype != 'T' && stype != 't')
		return 1;
	if (!strncmp("init_module", sym, 11) || !strncmp("cleanup_module", sym, 14))
		return 1;
	if (strstr(sym, "_text_start") || strstr(sym, "_text_end"))
		return 1;

	s->sym = malloc(strlen(str));
	assert(s->sym);

	strcpy((char *)s->sym, str);
	s->skip = 0;

	/* Tag events to be skipped. */
	if (!strcmp("default_idle", s->sym) || !strcmp("cpu_idle", s->sym))
		s->skip = 1;
	if (!strcmp("enter_idle", s->sym) || !strcmp("exit_idle", s->sym))
		s->skip = 1;

	if (filter_match == 1) {
		filter_end = s->addr;
		filter_match = -1;
		if (filter_end - filter_start > 10000) {
			printf("hm, too large filter symbol <%s> - skipping.\n",
				sym_filter);
			printf("symbol filter start: %016lx\n", filter_start);
			printf("                end: %016lx\n", filter_end);
			filter_end = filter_start = 0;
			sym_filter = NULL;
			sleep(1);
		}
	}
	if (filter_match == 0 && sym_filter && !strcmp(s->sym, sym_filter)) {
		filter_match = 1;
		filter_start = s->addr;
	}

	return 0;
}

int compare_addr(const void *__sym1, const void *__sym2)
{
	const struct sym_entry *sym1 = __sym1, *sym2 = __sym2;

	return sym1->addr > sym2->addr;
}

static void sort_symbol_table(void)
{
	int i, dups;

	do {
		qsort(sym_table, sym_table_count, sizeof(sym_table[0]), compare_addr);
		for (i = 0, dups = 0; i < sym_table_count; i++) {
			if (sym_table[i].addr == sym_table[i+1].addr) {
				sym_table[i+1].addr = -1ll;
				dups++;
			}
		}
		sym_table_count -= dups;
	} while(dups);
}

static void parse_symbols(void)
{
	struct sym_entry *last;

	FILE *kallsyms = fopen("/proc/kallsyms", "r");

	if (!kallsyms) {
		printf("Could not open /proc/kallsyms - no CONFIG_KALLSYMS_ALL=y?\n");
		exit(-1);
	}

	while (!feof(kallsyms)) {
		if (read_symbol(kallsyms, &sym_table[sym_table_count]) == 0) {
			sym_table_count++;
			assert(sym_table_count <= MAX_SYMS);
		}
	}

	sort_symbol_table();
	min_ip = sym_table[0].addr;
	max_ip = sym_table[sym_table_count-1].addr;
	last = sym_table + sym_table_count++;

	last->addr = -1ll;
	last->sym = "<end>";

	if (filter_end) {
		int count;
		for (count=0; count < sym_table_count; count ++) {
			if (!strcmp(sym_table[count].sym, sym_filter)) {
				sym_filter_entry = &sym_table[count];
				break;
			}
		}
	}
	if (dump_symtab) {
		int i;

		for (i = 0; i < sym_table_count; i++)
			fprintf(stderr, "%llx %s\n",
				sym_table[i].addr, sym_table[i].sym);
	}
}


static void parse_vmlinux(char *filename)
{
	FILE *file;
	char command[PATH_MAX*2];
	if (!filename)
		return;

	sprintf(command, "objdump --start-address=0x%016lx --stop-address=0x%016lx -dS %s", filter_start, filter_end, filename);

	file = popen(command, "r");
	if (!file)
		return;

	while (!feof(file)) {
		struct source_line *src;
		size_t dummy = 0;
		char *c;

		src = malloc(sizeof(struct source_line));
		assert(src != NULL);	
		memset(src, 0, sizeof(struct source_line));

		if (getline(&src->line, &dummy, file) < 0)
			break;
		if (!src->line)
			break;

		c = strchr(src->line, '\n');
		if (c)
			*c = 0;

		lines = g_list_prepend(lines, src);

		if (strlen(src->line)>8 && src->line[8] == ':')
			src->EIP = strtoull(src->line, NULL, 16);
		if (strlen(src->line)>8 && src->line[16] == ':')
			src->EIP = strtoull(src->line, NULL, 16);
	}
	pclose(file);
	lines = g_list_reverse(lines);
}

static void record_precise_ip(uint64_t ip)
{
	struct source_line *line;
	GList *item;

	item = g_list_first(lines);
	while (item) {
		line = item->data;
		if (line->EIP == ip)
			line->count++;
		if (line->EIP > ip)
			break;
		item = g_list_next(item);
	}
}

static void lookup_sym_in_vmlinux(struct sym_entry *sym)
{
	struct source_line *line;
	GList *item;
	char pattern[PATH_MAX];
	sprintf(pattern, "<%s>:", sym->sym);

	item = g_list_first(lines);
	while (item) {
		line = item->data;
		if (strstr(line->line, pattern)) {
			sym->source = item;
			break;
		}
		item = g_list_next(item);
	}
}

void show_lines(GList *item_queue, int item_queue_count)
{
	int i;
	struct source_line *line;

	for (i = 0; i < item_queue_count; i++) {
		line = item_queue->data;
		printf("%8li\t%s\n", line->count, line->line);
		item_queue = g_list_next(item_queue);
	}
}

#define TRACE_COUNT     3

static void show_details(struct sym_entry *sym)
{
	struct source_line *line;
	GList *item;
	int displayed = 0;
	GList *item_queue = NULL;
	int item_queue_count = 0;

	if (!sym->source)
		lookup_sym_in_vmlinux(sym);
	if (!sym->source)
		return;

	printf("Showing details for %s\n", sym->sym);

	item = sym->source;
	while (item) {
		line = item->data;
		if (displayed && strstr(line->line, ">:"))
			break;

		if (!item_queue_count)
			item_queue = item;
		item_queue_count ++;

		if (line->count >= count_filter) {
			show_lines(item_queue, item_queue_count);
			item_queue_count = 0;
			item_queue = NULL;
		} else if (item_queue_count > TRACE_COUNT) {
			item_queue = g_list_next(item_queue);
			item_queue_count --;
		}

		line->count = 0;
		displayed++;
		if (displayed > 300)
			break;
		item = g_list_next(item);
	}
}

/*
 * Binary search in the histogram table and record the hit:
 */
static void record_ip(uint64_t ip, int counter)
{
	int left_idx, middle_idx, right_idx, idx;
	unsigned long left, middle, right;

	record_precise_ip(ip);

	left_idx = 0;
	right_idx = sym_table_count-1;
	assert(ip <= max_ip && ip >= min_ip);

	while (left_idx + 1 < right_idx) {
		middle_idx = (left_idx + right_idx) / 2;

		left   = sym_table[  left_idx].addr;
		middle = sym_table[middle_idx].addr;
		right  = sym_table[ right_idx].addr;

		if (!(left <= middle && middle <= right)) {
			printf("%016lx...\n%016lx...\n%016lx\n", left, middle, right);
			printf("%d %d %d\n", left_idx, middle_idx, right_idx);
		}
		assert(left <= middle && middle <= right);
		if (!(left <= ip && ip <= right)) {
			printf(" left: %016lx\n", left);
			printf("   ip: %016lx\n", ip);
			printf("right: %016lx\n", right);
		}
		assert(left <= ip && ip <= right);
		/*
		 * [ left .... target .... middle .... right ]
		 *   => right := middle
		 */
		if (ip < middle) {
			right_idx = middle_idx;
			continue;
		}
		/*
		 * [ left .... middle ... target ... right ]
		 *   => left := middle
		 */
		left_idx = middle_idx;
	}

	idx = left_idx;

	if (!sym_table[idx].skip)
		sym_table[idx].count[counter]++;
	else events--;
}

static void process_event(uint64_t ip, int counter)
{
	events++;

	if (ip < min_ip || ip > max_ip) {
		userspace_events++;
		return;
	}

	record_ip(ip, counter);
}

int main(int argc, char *argv[])
{
	struct pollfd event_array[MAX_NR_CPUS][MAX_COUNTERS];
	struct perf_counter_hw_event hw_event;
	int fd[MAX_NR_CPUS][MAX_COUNTERS];
	int i, counter, group_fd;
	unsigned int cpu;
	uint64_t ip;
	ssize_t res;
	int ret;

	process_options(argc, argv);

	nr_cpus = sysconf(_SC_NPROCESSORS_ONLN);
	if (tid != -1 || profile_cpu != -1)
		nr_cpus = 1;

	assert(nr_cpus <= MAX_NR_CPUS);

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

			cpu	= profile_cpu;
			if (tid == -1 && profile_cpu == -1)
				cpu = i;

			memset(&hw_event, 0, sizeof(hw_event));
			hw_event.type		= event_id[counter];
			hw_event.raw		= event_raw[counter];
			hw_event.irq_period	= event_count[counter];
			hw_event.record_type	= PERF_RECORD_IRQ;
			hw_event.nmi		= nmi;

			fd[i][counter] = sys_perf_counter_open(&hw_event, tid, cpu, group_fd, 0);
			fcntl(fd[i][counter], F_SETFL, O_NONBLOCK);
			if (fd[i][counter] < 0) {
				printf("kerneltop error: syscall returned with %d (%s)\n",
					fd[i][counter], strerror(-fd[i][counter]));
				if (fd[i][counter] == -1)
					printf("Are you root?\n");
				exit(-1);
			}
			assert(fd[i][counter] >= 0);

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

			event_array[i][counter].fd = fd[i][counter];
			event_array[i][counter].events = POLLIN;
		}
	}

	parse_symbols();
	if (vmlinux && sym_filter_entry)
		parse_vmlinux(vmlinux);

	printf("KernelTop refresh period: %d seconds\n", delay_secs);
	last_refresh = time(NULL);

	while (1) {
		int hits = events;

		for (i = 0; i < nr_cpus; i++) {
			for (counter = 0; counter < nr_counters; counter++) {
				res = read(fd[i][counter], (char *) &ip, sizeof(ip));
				if (res > 0) {
					assert(res == sizeof(ip));

					process_event(ip, counter);
				}
			}
		}

		if (time(NULL) >= last_refresh + delay_secs) {
			print_sym_table();
			events = userspace_events = 0;
		}

		if (hits == events)
			ret = poll(event_array[0], nr_cpus, 1000);
		hits = events;
	}

	return 0;
}