diff --git a/Documentation/perf_counter/perf-record.c b/Documentation/perf_counter/perf-record.c
new file mode 100644
index 0000000..614de7c
--- /dev/null
+++ b/Documentation/perf_counter/perf-record.c
@@ -0,0 +1,530 @@
+
+
+#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;
+}