perf_counter: some simple userspace profiling (de9ac07b) · Commits · 戴 / test

Documentation/perf_counter/Makefile

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Original line number	Diff line number	Diff line
		BINS = kerneltop perfstat
		BINS = kerneltop perfstat perf-record perf-report

		all: $(BINS)

		kerneltop: kerneltop.c ../../include/linux/perf_counter.h
		cc -O6 -Wall -lrt -o $@ $<

		perf-record: perf-record.c ../../include/linux/perf_counter.h
		cc -O6 -Wall -lrt -o $@ $<

		perf-report: perf-report.cc ../../include/linux/perf_counter.h
		g++ -O6 -Wall -lrt -o $@ $<

		perfstat: kerneltop
		ln -sf kerneltop perfstat

Documentation/perf_counter/perf-record.c

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Original line number	Diff line number	Diff line


		#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 <limits.h>
		#include <getopt.h>
		#include <assert.h>
		#include <fcntl.h>
		#include <stdio.h>
		#include <errno.h>
		#include <ctype.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>

		#include "../../include/linux/perf_counter.h"


		/*
		* 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 ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))

		#define rdclock() \
		({ \
		struct timespec ts; \
		\
		clock_gettime(CLOCK_MONOTONIC, &ts); \
		ts.tv_sec * 1000000000ULL + ts.tv_nsec; \
		})

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

		#ifdef __x86_64__
		#define __NR_perf_counter_open 295
		#define rmb() asm volatile("lfence" ::: "memory")
		#define cpu_relax() asm volatile("rep; nop" ::: "memory");
		#endif

		#ifdef __i386__
		#define __NR_perf_counter_open 333
		#define rmb() asm volatile("lfence" ::: "memory")
		#define cpu_relax() asm volatile("rep; nop" ::: "memory");
		#endif

		#ifdef __powerpc__
		#define __NR_perf_counter_open 319
		#define rmb() asm volatile ("sync" ::: "memory")
		#define cpu_relax() asm volatile ("" ::: "memory");
		#endif

		#define unlikely(x) __builtin_expect(!!(x), 0)
		#define min(x, y) ({ \
		typeof(x) _min1 = (x); \
		typeof(y) _min2 = (y); \
		(void) (&_min1 == &_min2); \
		_min1 < _min2 ? _min1 : _min2; })

		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)
		{
		return syscall(
		__NR_perf_counter_open, hw_event_uptr, pid, cpu, group_fd, flags);
		}

		#define MAX_COUNTERS 64
		#define MAX_NR_CPUS 256

		#define EID(type, id) (((__u64)(type) << PERF_COUNTER_TYPE_SHIFT) \| (id))

		static int nr_counters = 0;
		static __u64 event_id[MAX_COUNTERS] = { };
		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 char *output_name = "output.perf";
		static int group = 0;
		static unsigned int realtime_prio = 0;

		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", },
		};

		/*
		* 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;
		}

		#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: perf-record [<options>]\n"
		"perf-record 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"
		" -m pages --mmap_pages=<pages> # number of mmap data pages\n"
		" -o file --output=<file> # output file\n"
		" -r prio --realtime=<prio> # use RT prio\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'},
		{"event", required_argument, NULL, 'e'},
		{"mmap_pages", required_argument, NULL, 'm'},
		{"output", required_argument, NULL, 'o'},
		{"realtime", required_argument, NULL, 'r'},
		{NULL, 0, NULL, 0 }
		};
		int c = getopt_long(argc, argv, "+:c:e:m:o:r:",
		long_options, &option_index);
		if (c == -1)
		break;

		switch (c) {
		case 'c': default_interval = atoi(optarg); break;
		case 'e': error = parse_events(optarg); break;
		case 'm': mmap_pages = atoi(optarg); break;
		case 'o': output_name = strdup(optarg); break;
		case 'r': realtime_prio = 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;
		}

		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 sigchld_handler(int sig)
		{
		if (sig == SIGCHLD)
		done = 1;
		}

		int main(int argc, char *argv[])
		{
		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;
		int i, counter, group_fd, nr_poll = 0;
		pid_t pid;
		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);

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

		argc -= optind;
		argv += optind;

		for (i = 0; i < nr_cpus; i++) {
		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 = 1;
		hw_event.mmap = 1;
		hw_event.comm = 1;

		fd[i][counter] = sys_perf_counter_open(&hw_event, -1, i, 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);
		}
		}
		}

		signal(SIGCHLD, sigchld_handler);

		pid = fork();
		if (pid < 0)
		perror("failed to fork");

		if (!pid) {
		if (execvp(argv[0], 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_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;
		}

Documentation/perf_counter/perf-report.cc

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Original line number	Diff line number	Diff line
		#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 <limits.h>
		#include <fcntl.h>
		#include <stdio.h>
		#include <errno.h>
		#include <ctype.h>
		#include <time.h>
		#include <getopt.h>

		#include <sys/ioctl.h>
		#include <sys/poll.h>
		#include <sys/prctl.h>
		#include <sys/wait.h>
		#include <sys/mman.h>
		#include <sys/types.h>
		#include <sys/stat.h>

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

		#include "../../include/linux/perf_counter.h"

		#include <set>
		#include <map>
		#include <string>


		static char const *input_name = "output.perf";
		static int input;

		static unsigned long page_size;
		static unsigned long mmap_window = 32;

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

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

		struct section {
		uint64_t start;
		uint64_t end;

		uint64_t offset;

		std::string name;

		section() { };

		section(uint64_t stab) : end(stab) { };

		section(uint64_t start, uint64_t size, uint64_t offset, std::string name) :
		start(start), end(start + size), offset(offset), name(name)
		{ };

		bool operator < (const struct section &s) const {
		return end < s.end;
		};
		};

		typedef std::set<struct section> sections_t;

		struct symbol {
		uint64_t start;
		uint64_t end;

		std::string name;

		symbol() { };

		symbol(uint64_t ip) : start(ip) { }

		symbol(uint64_t start, uint64_t len, std::string name) :
		start(start), end(start + len), name(name)
		{ };

		bool operator < (const struct symbol &s) const {
		return start < s.start;
		};
		};

		typedef std::set<struct symbol> symbols_t;

		struct dso {
		sections_t sections;
		symbols_t syms;
		};

		static std::map<std::string, struct dso> dsos;

		static void load_dso_sections(std::string dso_name)
		{
		struct dso &dso = dsos[dso_name];

		std::string cmd = "readelf -DSW " + dso_name;

		FILE *file = popen(cmd.c_str(), "r");
		if (!file) {
		perror("failed to open pipe");
		exit(-1);
		}

		char *line = NULL;
		size_t n = 0;

		while (!feof(file)) {
		uint64_t addr, off, size;
		char name[32];

		if (getline(&line, &n, file) < 0)
		break;
		if (!line)
		break;

		if (sscanf(line, " [%2d] %16s %14s %Lx %Lx %Lx",
		name, &addr, &off, &size) == 4) {

		dso.sections.insert(section(addr, size, addr - off, name));
		}
		#if 0
		/*
		* for reading readelf symbols (-s), however these don't seem
		* to include nearly everything, so use nm for that.
		*/
		if (sscanf(line, " %4d %3d: %Lx %5Lu %7s %6s %*7s %3d %s",
		&start, &size, &section, sym) == 4) {

		start -= dso.section_offsets[section];

		dso.syms.insert(symbol(start, size, std::string(sym)));
		}
		#endif
		}
		pclose(file);
		}

		static void load_dso_symbols(std::string dso_name, std::string args)
		{
		struct dso &dso = dsos[dso_name];

		std::string cmd = "nm -nSC " + args + " " + dso_name;

		FILE *file = popen(cmd.c_str(), "r");
		if (!file) {
		perror("failed to open pipe");
		exit(-1);
		}

		char *line = NULL;
		size_t n = 0;

		while (!feof(file)) {
		uint64_t start, size;
		char c;
		char sym[1024];

		if (getline(&line, &n, file) < 0)
		break;
		if (!line)
		break;


		if (sscanf(line, "%Lx %Lx %c %s", &start, &size, &c, sym) == 4) {
		sections_t::const_iterator si =
		dso.sections.upper_bound(section(start));
		if (si == dso.sections.end()) {
		printf("symbol in unknown section: %s\n", sym);
		continue;
		}

		start -= si->offset;

		dso.syms.insert(symbol(start, size, sym));
		}
		}
		pclose(file);
		}

		static void load_dso(std::string dso_name)
		{
		load_dso_sections(dso_name);
		load_dso_symbols(dso_name, "-D"); /* dynamic symbols */
		load_dso_symbols(dso_name, ""); /* regular ones */
		}

		void load_kallsyms(void)
		{
		struct dso &dso = dsos["[kernel]"];

		FILE *file = fopen("/proc/kallsyms", "r");
		if (!file) {
		perror("failed to open kallsyms");
		exit(-1);
		}

		char *line;
		size_t n;

		while (!feof(file)) {
		uint64_t start;
		char c;
		char sym[1024];

		if (getline(&line, &n, file) < 0)
		break;
		if (!line)
		break;

		if (sscanf(line, "%Lx %c %s", &start, &c, sym) == 3)
		dso.syms.insert(symbol(start, 0x1000000, std::string(sym)));
		}
		fclose(file);
		}

		struct map {
		uint64_t start;
		uint64_t end;
		uint64_t pgoff;

		std::string dso;

		map() { };

		map(uint64_t ip) : end(ip) { }

		map(mmap_event *mmap) {
		start = mmap->start;
		end = mmap->start + mmap->len;
		pgoff = mmap->pgoff;

		dso = std::string(mmap->filename);

		if (dsos.find(dso) == dsos.end())
		load_dso(dso);
		};

		bool operator < (const struct map &m) const {
		return end < m.end;
		};
		};

		typedef std::set<struct map> maps_t;

		static std::map<int, maps_t> maps;

		static std::map<int, std::string> comms;

		static std::map<std::string, int> hist;
		static std::multimap<int, std::string> rev_hist;

		static std::string resolve_comm(int pid)
		{
		std::string comm = "<unknown>";
		std::map<int, std::string>::const_iterator ci = comms.find(pid);
		if (ci != comms.end())
		comm = ci->second;

		return comm;
		}

		static std::string resolve_user_symbol(int pid, uint64_t ip)
		{
		std::string sym = "<unknown>";

		maps_t &m = maps[pid];
		maps_t::const_iterator mi = m.upper_bound(map(ip));
		if (mi == m.end())
		return sym;

		ip -= mi->start + mi->pgoff;

		symbols_t &s = dsos[mi->dso].syms;
		symbols_t::const_iterator si = s.upper_bound(symbol(ip));

		sym = mi->dso + ": <unknown>";

		if (si == s.begin())
		return sym;
		si--;

		if (si->start <= ip && ip < si->end)
		sym = mi->dso + ": " + si->name;
		#if 0
		else if (si->start <= ip)
		sym = mi->dso + ": ?" + si->name;
		#endif

		return sym;
		}

		static std::string resolve_kernel_symbol(uint64_t ip)
		{
		std::string sym = "<unknown>";

		symbols_t &s = dsos["[kernel]"].syms;
		symbols_t::const_iterator si = s.upper_bound(symbol(ip));

		if (si == s.begin())
		return sym;
		si--;

		if (si->start <= ip && ip < si->end)
		sym = si->name;

		return sym;
		}

		static void display_help(void)
		{
		printf(
		"Usage: perf-report [<options>]\n"
		" -i file --input=<file> # input file\n"
		);

		exit(0);
		}

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

		for (;;) {
		int option_index = 0;
		/** Options for getopt */
		static struct option long_options[] = {
		{"input", required_argument, NULL, 'i'},
		{NULL, 0, NULL, 0 }
		};
		int c = getopt_long(argc, argv, "+:i:",
		long_options, &option_index);
		if (c == -1)
		break;

		switch (c) {
		case 'i': input_name = strdup(optarg); break;
		default: error = 1; break;
		}
		}

		if (error)
		display_help();
		}

		int main(int argc, char *argv[])
		{
		unsigned long offset = 0;
		unsigned long head = 0;
		struct stat stat;
		char *buf;
		event_t *event;
		int ret;
		unsigned long total = 0;

		page_size = getpagesize();

		process_options(argc, argv);

		input = open(input_name, O_RDONLY);
		if (input < 0) {
		perror("failed to open file");
		exit(-1);
		}

		ret = fstat(input, &stat);
		if (ret < 0) {
		perror("failed to stat file");
		exit(-1);
		}

		load_kallsyms();

		remap:
		buf = (char )mmap(NULL, page_size mmap_window, PROT_READ,
		MAP_SHARED, input, offset);
		if (buf == MAP_FAILED) {
		perror("failed to mmap file");
		exit(-1);
		}

		more:
		event = (event_t *)(buf + head);

		if (head + event->header.size >= page_size * mmap_window) {
		unsigned long shift = page_size * (head / page_size);

		munmap(buf, page_size * mmap_window);
		offset += shift;
		head -= shift;
		goto remap;
		}
		head += event->header.size;

		if (event->header.misc & PERF_EVENT_MISC_OVERFLOW) {
		std::string comm, sym, level;
		char output[1024];

		if (event->header.misc & PERF_EVENT_MISC_KERNEL) {
		level = "[kernel]";
		sym = resolve_kernel_symbol(event->ip.ip);
		} else if (event->header.misc & PERF_EVENT_MISC_USER) {
		level = "[ user ]";
		sym = resolve_user_symbol(event->ip.pid, event->ip.ip);
		} else {
		level = "[ hv ]";
		}
		comm = resolve_comm(event->ip.pid);

		snprintf(output, sizeof(output), "%16s %s %s",
		comm.c_str(), level.c_str(), sym.c_str());
		hist[output]++;

		total++;

		} else switch (event->header.type) {
		case PERF_EVENT_MMAP:
		maps[event->mmap.pid].insert(map(&event->mmap));
		break;

		case PERF_EVENT_COMM:
		comms[event->comm.pid] = std::string(event->comm.comm);
		break;
		}

		if (offset + head < stat.st_size)
		goto more;

		close(input);

		std::map<std::string, int>::iterator hi = hist.begin();

		while (hi != hist.end()) {
		rev_hist.insert(std::pair<int, std::string>(hi->second, hi->first));
		hist.erase(hi++);
		}

		std::multimap<int, std::string>::const_iterator ri = rev_hist.begin();

		while (ri != rev_hist.end()) {
		printf(" %5.2f %s\n", (100.0 * ri->first)/total, ri->second.c_str());
		ri++;
		}

		return 0;
		}

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