path: root/Documentation/perf_counter/builtin-top.c

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

   Build with:

     make -C Documentation/perf_counter/

   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
 */

 /*
  * Copyright (C) 2008, Red Hat Inc, Ingo Molnar <mingo@redhat.com>
  *
  * Improvements and fixes by:
  *
  *   Arjan van de Ven <arjan@linux.intel.com>
  *   Yanmin Zhang <yanmin.zhang@intel.com>
  *   Wu Fengguang <fengguang.wu@intel.com>
  *   Mike Galbraith <efault@gmx.de>
  *   Paul Mackerras <paulus@samba.org>
  *
  * Released under the GPL v2. (and only v2, not any later version)
  */

#include "perf.h"
#include "util/util.h"

#include <getopt.h>
#include <assert.h>
#include <fcntl.h>
#include <stdio.h>
#include <errno.h>
#include <time.h>
#include <sched.h>
#include <pthread.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 <sys/mman.h>

#include <linux/unistd.h>
#include <linux/types.h>

static int			system_wide			=  0;

static int			nr_counters			=  0;
static __u64			event_id[MAX_COUNTERS]		= {
	EID(PERF_TYPE_SOFTWARE, PERF_COUNT_TASK_CLOCK),
	EID(PERF_TYPE_SOFTWARE, PERF_COUNT_CONTEXT_SWITCHES),
	EID(PERF_TYPE_SOFTWARE, PERF_COUNT_CPU_MIGRATIONS),
	EID(PERF_TYPE_SOFTWARE, PERF_COUNT_PAGE_FAULTS),

	EID(PERF_TYPE_HARDWARE, PERF_COUNT_CPU_CYCLES),
	EID(PERF_TYPE_HARDWARE, PERF_COUNT_INSTRUCTIONS),
	EID(PERF_TYPE_HARDWARE, PERF_COUNT_CACHE_REFERENCES),
	EID(PERF_TYPE_HARDWARE, PERF_COUNT_CACHE_MISSES),
};
static int			default_interval = 100000;
static int			event_count[MAX_COUNTERS];
static int			fd[MAX_NR_CPUS][MAX_COUNTERS];

static __u64			count_filter		       = 100;

static int			tid				= -1;
static int			profile_cpu			= -1;
static int			nr_cpus				=  0;
static int			nmi				=  1;
static unsigned int		realtime_prio			=  0;
static int			group				=  0;
static unsigned int		page_size;
static unsigned int		mmap_pages			=  16;
static int			use_mmap			= 0;
static int			use_munmap			= 0;
static int			freq				= 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;

static int			scale;

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

static struct source_line	*lines;
static struct source_line	**lines_tail;

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

static char *hw_event_names[] = {
	"CPU cycles",
	"instructions",
	"cache references",
	"cache misses",
	"branches",
	"branch misses",
	"bus cycles",
};

static char *sw_event_names[] = {
	"cpu clock ticks",
	"task clock ticks",
	"pagefaults",
	"context switches",
	"CPU migrations",
	"minor faults",
	"major faults",
};

struct event_symbol {
	__u64 event;
	char *symbol;
};

static struct event_symbol event_symbols[] = {
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_CPU_CYCLES),		"cpu-cycles",		},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_CPU_CYCLES),		"cycles",		},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_INSTRUCTIONS),		"instructions",		},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_CACHE_REFERENCES),		"cache-references",	},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_CACHE_MISSES),		"cache-misses",		},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_BRANCH_INSTRUCTIONS),	"branch-instructions",	},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_BRANCH_INSTRUCTIONS),	"branches",		},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_BRANCH_MISSES),		"branch-misses",	},
	{EID(PERF_TYPE_HARDWARE, PERF_COUNT_BUS_CYCLES),		"bus-cycles",		},

	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_CPU_CLOCK),			"cpu-clock",		},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_TASK_CLOCK),		"task-clock",		},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_PAGE_FAULTS),		"page-faults",		},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_PAGE_FAULTS),		"faults",		},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_PAGE_FAULTS_MIN),		"minor-faults",		},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_PAGE_FAULTS_MAJ),		"major-faults",		},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_CONTEXT_SWITCHES),		"context-switches",	},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_CONTEXT_SWITCHES),		"cs",			},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_CPU_MIGRATIONS),		"cpu-migrations",	},
	{EID(PERF_TYPE_SOFTWARE, PERF_COUNT_CPU_MIGRATIONS),		"migrations",		},
};

#define __PERF_COUNTER_FIELD(config, name) \
	((config & PERF_COUNTER_##name##_MASK) >> PERF_COUNTER_##name##_SHIFT)

#define PERF_COUNTER_RAW(config)	__PERF_COUNTER_FIELD(config, RAW)
#define PERF_COUNTER_CONFIG(config)	__PERF_COUNTER_FIELD(config, CONFIG)
#define PERF_COUNTER_TYPE(config)	__PERF_COUNTER_FIELD(config, TYPE)
#define PERF_COUNTER_ID(config)		__PERF_COUNTER_FIELD(config, EVENT)

static void display_events_help(void)
{
	unsigned int i;
	__u64 e;

	printf(
	" -e EVENT     --event=EVENT   #  symbolic-name        abbreviations");

	for (i = 0; i < ARRAY_SIZE(event_symbols); i++) {
		int type, id;

		e = event_symbols[i].event;
		type = PERF_COUNTER_TYPE(e);
		id = PERF_COUNTER_ID(e);

		printf("\n                             %d:%d: %-20s",
				type, id, event_symbols[i].symbol);
	}

	printf("\n"
	"                           rNNN: raw PMU events (eventsel+umask)\n\n");
}

static void display_help(void)
{
	printf(
	"Usage: kerneltop [<options>]\n"
	"   Or: kerneltop -S [<options>] COMMAND [ARGS]\n\n"
	"KernelTop Options (up to %d event types can be specified at once):\n\n",
		 MAX_COUNTERS);

	display_events_help();

	printf(
	" -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"
	" -l                           # show scale factor for RR events\n"
	" -d delay  --delay=<seconds>  # sampling/display delay           [default:  2]\n"
	" -f CNT    --filter=CNT       # min-event-count filter          [default: 100]\n\n"
	" -r prio   --realtime=<prio>  # event acquisition runs with SCHED_FIFO policy\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"
	" -m pages  --mmap_pages=<pages> # number of mmap data pages\n"
	" -M        --mmap_info        # print mmap info stream\n"
	" -U        --munmap_info      # print munmap info stream\n"
	);

	exit(0);
}

static char *event_name(int ctr)
{
	__u64 config = event_id[ctr];
	int type = PERF_COUNTER_TYPE(config);
	int id = PERF_COUNTER_ID(config);
	static char buf[32];

	if (PERF_COUNTER_RAW(config)) {
		sprintf(buf, "raw 0x%llx", PERF_COUNTER_CONFIG(config));
		return buf;
	}

	switch (type) {
	case PERF_TYPE_HARDWARE:
		if (id < PERF_HW_EVENTS_MAX)
			return hw_event_names[id];
		return "unknown-hardware";

	case PERF_TYPE_SOFTWARE:
		if (id < PERF_SW_EVENTS_MAX)
			return sw_event_names[id];
		return "unknown-software";

	default:
		break;
	}

	return "unknown";
}

/*
 * Each event can have multiple symbolic names.
 * Symbolic names are (almost) exactly matched.
 */
static __u64 match_event_symbols(char *str)
{
	__u64 config, id;
	int type;
	unsigned int i;

	if (sscanf(str, "r%llx", &config) == 1)
		return config | PERF_COUNTER_RAW_MASK;

	if (sscanf(str, "%d:%llu", &type, &id) == 2)
		return EID(type, id);

	for (i = 0; i < ARRAY_SIZE(event_symbols); i++) {
		if (!strncmp(str, event_symbols[i].symbol,
			     strlen(event_symbols[i].symbol)))
			return event_symbols[i].event;
	}

	return ~0ULL;
}

static int parse_events(char *str)
{
	__u64 config;

again:
	if (nr_counters == MAX_COUNTERS)
		return -1;

	config = match_event_symbols(str);
	if (config == ~0ULL)
		return -1;

	event_id[nr_counters] = config;
	nr_counters++;

	str = strstr(str, ",");
	if (str) {
		str++;
		goto again;
	}

	return 0;
}

/*
 * Symbols
 */

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;
	struct source_line	*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-2 * ... / 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 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;
	float sum_kevents = 0.0;

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

	for (i = 0; i < sym_table_count && tmp[i].count[0]; i++)
		sum_kevents += tmp[i].count[0];

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

	printf(
"------------------------------------------------------------------------------\n");
	printf( " KernelTop:%8.0f irqs/sec  kernel:%4.1f%% [%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("/");

		printf("%s", event_name(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    pcnt");
	else
		printf("  weight     events    pcnt");

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

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

		if (printed <= 18 && tmp[i].count[0] >= count_filter) {
			pcnt = 100.0 - (100.0*((sum_kevents-tmp[i].count[0])/sum_kevents));

			if (nr_counters == 1)
				printf("%19.2f - %4.1f%% - %016llx : %s\n",
					sym_weight(tmp + i),
					pcnt, tmp[i].addr, tmp[i].sym);
			else
				printf("%8.1f %10ld - %4.1f%% - %016llx : %s\n",
					sym_weight(tmp + i),
					tmp[i].count[0],
					pcnt, 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);

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

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

static void *display_thread(void *arg)
{
	printf("KernelTop refresh period: %d seconds\n", delay_secs);

	while (!sleep(delay_secs))
		print_sym_table();

	return NULL;
}

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)+1);
	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;
	else if (!strcmp("enter_idle", s->sym) || !strcmp("exit_idle", s->sym))
		s->skip = 1;
	else if (!strcmp("mwait_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;
}

static 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);
	}
}

/*
 * Source lines
 */

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;

	lines_tail = &lines;
	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;

		src->next = NULL;
		*lines_tail = src;
		lines_tail = &src->next;

		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);
}

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

	for (line = lines; line; line = line->next) {
		if (line->EIP == ip)
			line->count++;
		if (line->EIP > ip)
			break;
	}
}

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

	for (line = lines; line; line = line->next) {
		if (strstr(line->line, pattern)) {
			sym->source = line;
			break;
		}
	}
}

static void show_lines(struct source_line *line_queue, int line_queue_count)
{
	int i;
	struct source_line *line;

	line = line_queue;
	for (i = 0; i < line_queue_count; i++) {
		printf("%8li\t%s\n", line->count, line->line);
		line = line->next;
	}
}

#define TRACE_COUNT     3

static void show_details(struct sym_entry *sym)
{
	struct source_line *line;
	struct source_line *line_queue = NULL;
	int displayed = 0;
	int line_queue_count = 0;

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

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

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

		if (!line_queue_count)
			line_queue = line;
		line_queue_count ++;

		if (line->count >= count_filter) {
			show_lines(line_queue, line_queue_count);
			line_queue_count = 0;
			line_queue = NULL;
		} else if (line_queue_count > TRACE_COUNT) {
			line_queue = line_queue->next;
			line_queue_count --;
		}

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

/*
 * 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", (unsigned long)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);
}

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",	required_argument,	NULL, 'e'},
			{"filter",	required_argument,	NULL, 'f'},
			{"group",	required_argument,	NULL, 'g'},
			{"help",	no_argument,		NULL, 'h'},
			{"nmi",		required_argument,	NULL, 'n'},
			{"mmap_info",	no_argument,		NULL, 'M'},
			{"mmap_pages",	required_argument,	NULL, 'm'},
			{"munmap_info",	no_argument,		NULL, 'U'},
			{"pid",		required_argument,	NULL, 'p'},
			{"realtime",	required_argument,	NULL, 'r'},
			{"scale",	no_argument,		NULL, 'l'},
			{"symbol",	required_argument,	NULL, 's'},
			{"stat",	no_argument,		NULL, 'S'},
			{"vmlinux",	required_argument,	NULL, 'x'},
			{"zero",	no_argument,		NULL, 'z'},
			{"freq",	required_argument,	NULL, 'F'},
			{NULL,		0,			NULL,  0 }
		};
		int c = getopt_long(argc, argv, "+:ac:C:d:De:f:g:hln:m:p:r:s:Sx:zMUF:",
				    long_options, &option_index);
		if (c == -1)
			break;

		switch (c) {
		case 'a': system_wide			=	       1; break;
		case 'c': default_interval		=   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': error				= parse_events(optarg); break;

		case 'f': count_filter			=   atoi(optarg); break;
		case 'g': group				=   atoi(optarg); break;
		case 'h':      				  display_help(); break;
		case 'l': scale				=	       1; 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 'r': realtime_prio			=   atoi(optarg); break;
		case 's': sym_filter			= strdup(optarg); break;
		case 'x': vmlinux			= strdup(optarg); break;
		case 'z': zero				=              1; break;
		case 'm': mmap_pages			=   atoi(optarg); break;
		case 'M': use_mmap			=              1; break;
		case 'U': use_munmap			=              1; break;
		case 'F': freq = 1; default_interval	=   atoi(optarg); break;
		default: error = 1; break;
		}
	}
	if (error)
		display_help();

	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;
	}
}

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;
}

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;
	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;

	for (; old != head;) {
		struct ip_event {
			struct perf_event_header header;
			__u64 ip;
			__u32 pid, tid;
		};
		struct mmap_event {
			struct perf_event_header header;
			__u32 pid, tid;
			__u64 start;
			__u64 len;
			__u64 pgoff;
			char filename[PATH_MAX];
		};

		typedef union event_union {
			struct perf_event_header header;
			struct ip_event ip;
			struct mmap_event mmap;
		} event_t;

		event_t *event = (event_t *)&data[old & md->mask];

		event_t event_copy;

		size_t size = event->header.size;

		/*
		 * Event straddles the mmap boundary -- header should always
		 * be inside due to u64 alignment of output.
		 */
		if ((old & md->mask) + size != ((old + size) & md->mask)) {
			unsigned int offset = old;
			unsigned int len = min(sizeof(*event), size), cpy;
			void *dst = &event_copy;

			do {
				cpy = min(md->mask + 1 - (offset & md->mask), len);
				memcpy(dst, &data[offset & md->mask], cpy);
				offset += cpy;
				dst += cpy;
				len -= cpy;
			} while (len);

			event = &event_copy;
		}

		old += size;

		if (event->header.misc & PERF_EVENT_MISC_OVERFLOW) {
			if (event->header.type & PERF_RECORD_IP)
				process_event(event->ip.ip, md->counter);
		} else {
			switch (event->header.type) {
				case PERF_EVENT_MMAP:
				case PERF_EVENT_MUNMAP:
					printf("%s: %Lu %Lu %Lu %s\n",
							event->header.type == PERF_EVENT_MMAP
							? "mmap" : "munmap",
							event->mmap.start,
							event->mmap.len,
							event->mmap.pgoff,
							event->mmap.filename);
					break;
			}
		}
	}

	md->prev = old;
}

int cmd_top(int argc, char **argv, const char *prefix)
{
	struct pollfd event_array[MAX_NR_CPUS * MAX_COUNTERS];
	struct mmap_data mmap_array[MAX_NR_CPUS][MAX_COUNTERS];
	struct perf_counter_hw_event hw_event;
	pthread_t thread;
	int i, counter, group_fd, nr_poll = 0;
	unsigned int cpu;
	int ret;

	page_size = sysconf(_SC_PAGE_SIZE);

	process_options(argc, argv);

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

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

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

	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.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		= use_mmap;
			hw_event.munmap		= use_munmap;
			hw_event.freq		= freq;

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

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

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

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

	if (pthread_create(&thread, NULL, display_thread, NULL)) {
		printf("Could not create display thread.\n");
		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);
		}
	}

	while (1) {
		int hits = events;

		for (i = 0; i < nr_cpus; 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;
}