perf timechart: Implement IO mode

Currently, timechart records only scheduler and CPU events (task switches,
running times, CPU power states, etc); this commit adds IO mode which
makes it possible to record IO (disk, network) activity. In this mode
perf timechart will generate SVG with IO charts (writes, reads, tx, rx, polls).

Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/n/1404835423-23098-3-git-send-email-stfomichev@yandex-team.ru
Signed-off-by: Jiri Olsa <jolsa@kernel.org>

1 files changed, 602 insertions, 18 deletions

diff --git a/tools/perf/builtin-timechart.c b/tools/perf/builtin-timechart.c
index 74db2568b867..4079062d25b0 100644
--- a/tools/perf/builtin-timechart.c
+++ b/tools/perf/builtin-timechart.c
@@ -60,10 +60,14 @@ struct timechart {
 				tasks_only,
 				with_backtrace,
 				topology;
+	/* IO related settings */
+	u64			io_events;
+	bool			io_only;
 };
 
 struct per_pidcomm;
 struct cpu_sample;
+struct io_sample;
 
 /*
  * Datastructure layout:
@@ -84,6 +88,7 @@ struct per_pid {
 	u64		start_time;
 	u64		end_time;
 	u64		total_time;
+	u64		total_bytes;
 	int		display;
 
 	struct per_pidcomm *all;
@@ -97,6 +102,8 @@ struct per_pidcomm {
 	u64		start_time;
 	u64		end_time;
 	u64		total_time;
+	u64		max_bytes;
+	u64		total_bytes;
 
 	int		Y;
 	int		display;
@@ -107,6 +114,7 @@ struct per_pidcomm {
 	char		*comm;
 
 	struct cpu_sample *samples;
+	struct io_sample  *io_samples;
 };
 
 struct sample_wrapper {
@@ -131,6 +139,27 @@ struct cpu_sample {
 	const char *backtrace;
 };
 
+enum {
+	IOTYPE_READ,
+	IOTYPE_WRITE,
+	IOTYPE_SYNC,
+	IOTYPE_TX,
+	IOTYPE_RX,
+	IOTYPE_POLL,
+};
+
+struct io_sample {
+	struct io_sample *next;
+
+	u64 start_time;
+	u64 end_time;
+	u64 bytes;
+	int type;
+	int fd;
+	int err;
+	int merges;
+};
+
 #define CSTATE 1
 #define PSTATE 2
 
@@ -682,6 +711,219 @@ static void end_sample_processing(struct timechart *tchart)
 	}
 }
 
+static int pid_begin_io_sample(struct timechart *tchart, int pid, int type,
+			       u64 start, int fd)
+{
+	struct per_pid *p = find_create_pid(tchart, pid);
+	struct per_pidcomm *c = p->current;
+	struct io_sample *sample;
+	struct io_sample *prev;
+
+	if (!c) {
+		c = zalloc(sizeof(*c));
+		if (!c)
+			return -ENOMEM;
+		p->current = c;
+		c->next = p->all;
+		p->all = c;
+	}
+
+	prev = c->io_samples;
+
+	if (prev && prev->start_time && !prev->end_time) {
+		pr_warning("Skip invalid start event: "
+			   "previous event already started!\n");
+
+		/* remove previous event that has been started,
+		 * we are not sure we will ever get an end for it */
+		c->io_samples = prev->next;
+		free(prev);
+		return 0;
+	}
+
+	sample = zalloc(sizeof(*sample));
+	if (!sample)
+		return -ENOMEM;
+	sample->start_time = start;
+	sample->type = type;
+	sample->fd = fd;
+	sample->next = c->io_samples;
+	c->io_samples = sample;
+
+	if (c->start_time == 0 || c->start_time > start)
+		c->start_time = start;
+
+	return 0;
+}
+
+static int pid_end_io_sample(struct timechart *tchart, int pid, int type,
+			     u64 end, long ret)
+{
+	struct per_pid *p = find_create_pid(tchart, pid);
+	struct per_pidcomm *c = p->current;
+	struct io_sample *sample;
+
+	if (!c) {
+		pr_warning("Invalid pidcomm!\n");
+		return -1;
+	}
+
+	sample = c->io_samples;
+
+	if (!sample) /* skip partially captured events */
+		return 0;
+
+	if (sample->end_time) {
+		pr_warning("Skip invalid end event: "
+			   "previous event already ended!\n");
+		return 0;
+	}
+
+	if (sample->type != type) {
+		pr_warning("Skip invalid end event: invalid event type!\n");
+		return 0;
+	}
+
+	sample->end_time = end;
+
+	if (ret < 0) {
+		sample->err = ret;
+	} else if (type == IOTYPE_READ || type == IOTYPE_WRITE ||
+		   type == IOTYPE_TX || type == IOTYPE_RX) {
+
+		if ((u64)ret > c->max_bytes)
+			c->max_bytes = ret;
+
+		c->total_bytes += ret;
+		p->total_bytes += ret;
+		sample->bytes = ret;
+	}
+
+	tchart->io_events++;
+
+	return 0;
+}
+
+static int
+process_enter_read(struct timechart *tchart,
+		   struct perf_evsel *evsel,
+		   struct perf_sample *sample)
+{
+	long fd = perf_evsel__intval(evsel, sample, "fd");
+	return pid_begin_io_sample(tchart, sample->tid, IOTYPE_READ,
+				   sample->time, fd);
+}
+
+static int
+process_exit_read(struct timechart *tchart,
+		  struct perf_evsel *evsel,
+		  struct perf_sample *sample)
+{
+	long ret = perf_evsel__intval(evsel, sample, "ret");
+	return pid_end_io_sample(tchart, sample->tid, IOTYPE_READ,
+				 sample->time, ret);
+}
+
+static int
+process_enter_write(struct timechart *tchart,
+		    struct perf_evsel *evsel,
+		    struct perf_sample *sample)
+{
+	long fd = perf_evsel__intval(evsel, sample, "fd");
+	return pid_begin_io_sample(tchart, sample->tid, IOTYPE_WRITE,
+				   sample->time, fd);
+}
+
+static int
+process_exit_write(struct timechart *tchart,
+		   struct perf_evsel *evsel,
+		   struct perf_sample *sample)
+{
+	long ret = perf_evsel__intval(evsel, sample, "ret");
+	return pid_end_io_sample(tchart, sample->tid, IOTYPE_WRITE,
+				 sample->time, ret);
+}
+
+static int
+process_enter_sync(struct timechart *tchart,
+		   struct perf_evsel *evsel,
+		   struct perf_sample *sample)
+{
+	long fd = perf_evsel__intval(evsel, sample, "fd");
+	return pid_begin_io_sample(tchart, sample->tid, IOTYPE_SYNC,
+				   sample->time, fd);
+}
+
+static int
+process_exit_sync(struct timechart *tchart,
+		  struct perf_evsel *evsel,
+		  struct perf_sample *sample)
+{
+	long ret = perf_evsel__intval(evsel, sample, "ret");
+	return pid_end_io_sample(tchart, sample->tid, IOTYPE_SYNC,
+				 sample->time, ret);
+}
+
+static int
+process_enter_tx(struct timechart *tchart,
+		 struct perf_evsel *evsel,
+		 struct perf_sample *sample)
+{
+	long fd = perf_evsel__intval(evsel, sample, "fd");
+	return pid_begin_io_sample(tchart, sample->tid, IOTYPE_TX,
+				   sample->time, fd);
+}
+
+static int
+process_exit_tx(struct timechart *tchart,
+		struct perf_evsel *evsel,
+		struct perf_sample *sample)
+{
+	long ret = perf_evsel__intval(evsel, sample, "ret");
+	return pid_end_io_sample(tchart, sample->tid, IOTYPE_TX,
+				 sample->time, ret);
+}
+
+static int
+process_enter_rx(struct timechart *tchart,
+		 struct perf_evsel *evsel,
+		 struct perf_sample *sample)
+{
+	long fd = perf_evsel__intval(evsel, sample, "fd");
+	return pid_begin_io_sample(tchart, sample->tid, IOTYPE_RX,
+				   sample->time, fd);
+}
+
+static int
+process_exit_rx(struct timechart *tchart,
+		struct perf_evsel *evsel,
+		struct perf_sample *sample)
+{
+	long ret = perf_evsel__intval(evsel, sample, "ret");
+	return pid_end_io_sample(tchart, sample->tid, IOTYPE_RX,
+				 sample->time, ret);
+}
+
+static int
+process_enter_poll(struct timechart *tchart,
+		   struct perf_evsel *evsel,
+		   struct perf_sample *sample)
+{
+	long fd = perf_evsel__intval(evsel, sample, "fd");
+	return pid_begin_io_sample(tchart, sample->tid, IOTYPE_POLL,
+				   sample->time, fd);
+}
+
+static int
+process_exit_poll(struct timechart *tchart,
+		  struct perf_evsel *evsel,
+		  struct perf_sample *sample)
+{
+	long ret = perf_evsel__intval(evsel, sample, "ret");
+	return pid_end_io_sample(tchart, sample->tid, IOTYPE_POLL,
+				 sample->time, ret);
+}
+
 /*
  * Sort the pid datastructure
  */
@@ -852,6 +1094,117 @@ static void draw_cpu_usage(struct timechart *tchart)
 	}
 }
 
+static void draw_io_bars(struct timechart *tchart)
+{
+	const char *suf;
+	double bytes;
+	char comm[256];
+	struct per_pid *p;
+	struct per_pidcomm *c;
+	struct io_sample *sample;
+	int Y = 1;
+
+	p = tchart->all_data;
+	while (p) {
+		c = p->all;
+		while (c) {
+			if (!c->display) {
+				c->Y = 0;
+				c = c->next;
+				continue;
+			}
+
+			svg_box(Y, c->start_time, c->end_time, "process3");
+			sample = c->io_samples;
+			for (sample = c->io_samples; sample; sample = sample->next) {
+				double h = (double)sample->bytes / c->max_bytes;
+
+				if (sample->err)
+					h = 1;
+
+				if (sample->type == IOTYPE_SYNC)
+					svg_fbox(Y,
+						sample->start_time,
+						sample->end_time,
+						1,
+						sample->err ? "error" : "sync",
+						sample->fd,
+						sample->err,
+						sample->merges);
+				else if (sample->type == IOTYPE_POLL)
+					svg_fbox(Y,
+						sample->start_time,
+						sample->end_time,
+						1,
+						sample->err ? "error" : "poll",
+						sample->fd,
+						sample->err,
+						sample->merges);
+				else if (sample->type == IOTYPE_READ)
+					svg_ubox(Y,
+						sample->start_time,
+						sample->end_time,
+						h,
+						sample->err ? "error" : "disk",
+						sample->fd,
+						sample->err,
+						sample->merges);
+				else if (sample->type == IOTYPE_WRITE)
+					svg_lbox(Y,
+						sample->start_time,
+						sample->end_time,
+						h,
+						sample->err ? "error" : "disk",
+						sample->fd,
+						sample->err,
+						sample->merges);
+				else if (sample->type == IOTYPE_RX)
+					svg_ubox(Y,
+						sample->start_time,
+						sample->end_time,
+						h,
+						sample->err ? "error" : "net",
+						sample->fd,
+						sample->err,
+						sample->merges);
+				else if (sample->type == IOTYPE_TX)
+					svg_lbox(Y,
+						sample->start_time,
+						sample->end_time,
+						h,
+						sample->err ? "error" : "net",
+						sample->fd,
+						sample->err,
+						sample->merges);
+			}
+
+			suf = "";
+			bytes = c->total_bytes;
+			if (bytes > 1024) {
+				bytes = bytes / 1024;
+				suf = "K";
+			}
+			if (bytes > 1024) {
+				bytes = bytes / 1024;
+				suf = "M";
+			}
+			if (bytes > 1024) {
+				bytes = bytes / 1024;
+				suf = "G";
+			}
+
+
+			sprintf(comm, "%s:%i (%3.1f %sbytes)", c->comm ?: "", p->pid, bytes, suf);
+			svg_text(Y, c->start_time, comm);
+
+			c->Y = Y;
+			Y++;
+			c = c->next;
+		}
+		p = p->next;
+	}
+}
+
 static void draw_process_bars(struct timechart *tchart)
 {
 	struct per_pid *p;
@@ -987,9 +1340,6 @@ static int determine_display_tasks(struct timechart *tchart, u64 threshold)
 	struct per_pidcomm *c;
 	int count = 0;
 
-	if (process_filter)
-		return determine_display_tasks_filtered(tchart);
-
 	p = tchart->all_data;
 	while (p) {
 		p->display = 0;
@@ -1025,15 +1375,46 @@ static int determine_display_tasks(struct timechart *tchart, u64 threshold)
 	return count;
 }
 
+static int determine_display_io_tasks(struct timechart *timechart, u64 threshold)
+{
+	struct per_pid *p;
+	struct per_pidcomm *c;
+	int count = 0;
+
+	p = timechart->all_data;
+	while (p) {
+		/* no exit marker, task kept running to the end */
+		if (p->end_time == 0)
+			p->end_time = timechart->last_time;
+
+		c = p->all;
+
+		while (c) {
+			c->display = 0;
+
+			if (c->total_bytes >= threshold) {
+				c->display = 1;
+				count++;
+			}
 
+			if (c->end_time == 0)
+				c->end_time = timechart->last_time;
+
+			c = c->next;
+		}
+		p = p->next;
+	}
+	return count;
+}
 
+#define BYTES_THRESH (1 * 1024 * 1024)
 #define TIME_THRESH 10000000
 
 static void write_svg_file(struct timechart *tchart, const char *filename)
 {
 	u64 i;
 	int count;
-	int thresh = TIME_THRESH;
+	int thresh = tchart->io_events ? BYTES_THRESH : TIME_THRESH;
 
 	if (tchart->power_only)
 		tchart->proc_num = 0;
@@ -1041,28 +1422,43 @@ static void write_svg_file(struct timechart *tchart, const char *filename)
 	/* We'd like to show at least proc_num tasks;
 	 * be less picky if we have fewer */
 	do {
-		count = determine_display_tasks(tchart, thresh);
+		if (process_filter)
+			count = determine_display_tasks_filtered(tchart);
+		else if (tchart->io_events)
+			count = determine_display_io_tasks(tchart, thresh);
+		else
+			count = determine_display_tasks(tchart, thresh);
 		thresh /= 10;
 	} while (!process_filter && thresh && count < tchart->proc_num);
 
 	if (!tchart->proc_num)
 		count = 0;
 
-	open_svg(filename, tchart->numcpus, count, tchart->first_time, tchart->last_time);
+	if (tchart->io_events) {
+		open_svg(filename, 0, count, tchart->first_time, tchart->last_time);
 
-	svg_time_grid();
-	svg_legenda();
+		svg_time_grid(0.5);
+		svg_io_legenda();
 
-	for (i = 0; i < tchart->numcpus; i++)
-		svg_cpu_box(i, tchart->max_freq, tchart->turbo_frequency);
+		draw_io_bars(tchart);
+	} else {
+		open_svg(filename, tchart->numcpus, count, tchart->first_time, tchart->last_time);
 
-	draw_cpu_usage(tchart);
-	if (tchart->proc_num)
-		draw_process_bars(tchart);
-	if (!tchart->tasks_only)
-		draw_c_p_states(tchart);
-	if (tchart->proc_num)
-		draw_wakeups(tchart);
+		svg_time_grid(0);
+
+		svg_legenda();
+
+		for (i = 0; i < tchart->numcpus; i++)
+			svg_cpu_box(i, tchart->max_freq, tchart->turbo_frequency);
+
+		draw_cpu_usage(tchart);
+		if (tchart->proc_num)
+			draw_process_bars(tchart);
+		if (!tchart->tasks_only)
+			draw_c_p_states(tchart);
+		if (tchart->proc_num)
+			draw_wakeups(tchart);
+	}
 
 	svg_close();
 }
@@ -1110,6 +1506,56 @@ static int __cmd_timechart(struct timechart *tchart, const char *output_name)
 		{ "power:power_end",		process_sample_power_end },
 		{ "power:power_frequency",	process_sample_power_frequency },
 #endif
+
+		{ "syscalls:sys_enter_read",		process_enter_read },
+		{ "syscalls:sys_enter_pread64",		process_enter_read },
+		{ "syscalls:sys_enter_readv",		process_enter_read },
+		{ "syscalls:sys_enter_preadv",		process_enter_read },
+		{ "syscalls:sys_enter_write",		process_enter_write },
+		{ "syscalls:sys_enter_pwrite64",	process_enter_write },
+		{ "syscalls:sys_enter_writev",		process_enter_write },
+		{ "syscalls:sys_enter_pwritev",		process_enter_write },
+		{ "syscalls:sys_enter_sync",		process_enter_sync },
+		{ "syscalls:sys_enter_sync_file_range",	process_enter_sync },
+		{ "syscalls:sys_enter_fsync",		process_enter_sync },
+		{ "syscalls:sys_enter_msync",		process_enter_sync },
+		{ "syscalls:sys_enter_recvfrom",	process_enter_rx },
+		{ "syscalls:sys_enter_recvmmsg",	process_enter_rx },
+		{ "syscalls:sys_enter_recvmsg",		process_enter_rx },
+		{ "syscalls:sys_enter_sendto",		process_enter_tx },
+		{ "syscalls:sys_enter_sendmsg",		process_enter_tx },
+		{ "syscalls:sys_enter_sendmmsg",	process_enter_tx },
+		{ "syscalls:sys_enter_epoll_pwait",	process_enter_poll },
+		{ "syscalls:sys_enter_epoll_wait",	process_enter_poll },
+		{ "syscalls:sys_enter_poll",		process_enter_poll },
+		{ "syscalls:sys_enter_ppoll",		process_enter_poll },
+		{ "syscalls:sys_enter_pselect6",	process_enter_poll },
+		{ "syscalls:sys_enter_select",		process_enter_poll },
+
+		{ "syscalls:sys_exit_read",		process_exit_read },
+		{ "syscalls:sys_exit_pread64",		process_exit_read },
+		{ "syscalls:sys_exit_readv",		process_exit_read },
+		{ "syscalls:sys_exit_preadv",		process_exit_read },
+		{ "syscalls:sys_exit_write",		process_exit_write },
+		{ "syscalls:sys_exit_pwrite64",		process_exit_write },
+		{ "syscalls:sys_exit_writev",		process_exit_write },
+		{ "syscalls:sys_exit_pwritev",		process_exit_write },
+		{ "syscalls:sys_exit_sync",		process_exit_sync },
+		{ "syscalls:sys_exit_sync_file_range",	process_exit_sync },
+		{ "syscalls:sys_exit_fsync",		process_exit_sync },
+		{ "syscalls:sys_exit_msync",		process_exit_sync },
+		{ "syscalls:sys_exit_recvfrom",		process_exit_rx },
+		{ "syscalls:sys_exit_recvmmsg",		process_exit_rx },
+		{ "syscalls:sys_exit_recvmsg",		process_exit_rx },
+		{ "syscalls:sys_exit_sendto",		process_exit_tx },
+		{ "syscalls:sys_exit_sendmsg",		process_exit_tx },
+		{ "syscalls:sys_exit_sendmmsg",		process_exit_tx },
+		{ "syscalls:sys_exit_epoll_pwait",	process_exit_poll },
+		{ "syscalls:sys_exit_epoll_wait",	process_exit_poll },
+		{ "syscalls:sys_exit_poll",		process_exit_poll },
+		{ "syscalls:sys_exit_ppoll",		process_exit_poll },
+		{ "syscalls:sys_exit_pselect6",		process_exit_poll },
+		{ "syscalls:sys_exit_select",		process_exit_poll },
 	};
 	struct perf_data_file file = {
 		.path = input_name,
@@ -1154,6 +1600,139 @@ out_delete:
 	return ret;
 }
 
+static int timechart__io_record(int argc, const char **argv)
+{
+	unsigned int rec_argc, i;
+	const char **rec_argv;
+	const char **p;
+	char *filter = NULL;
+
+	const char * const common_args[] = {
+		"record", "-a", "-R", "-c", "1",
+	};
+	unsigned int common_args_nr = ARRAY_SIZE(common_args);
+
+	const char * const disk_events[] = {
+		"syscalls:sys_enter_read",
+		"syscalls:sys_enter_pread64",
+		"syscalls:sys_enter_readv",
+		"syscalls:sys_enter_preadv",
+		"syscalls:sys_enter_write",
+		"syscalls:sys_enter_pwrite64",
+		"syscalls:sys_enter_writev",
+		"syscalls:sys_enter_pwritev",
+		"syscalls:sys_enter_sync",
+		"syscalls:sys_enter_sync_file_range",
+		"syscalls:sys_enter_fsync",
+		"syscalls:sys_enter_msync",
+
+		"syscalls:sys_exit_read",
+		"syscalls:sys_exit_pread64",
+		"syscalls:sys_exit_readv",
+		"syscalls:sys_exit_preadv",
+		"syscalls:sys_exit_write",
+		"syscalls:sys_exit_pwrite64",
+		"syscalls:sys_exit_writev",
+		"syscalls:sys_exit_pwritev",
+		"syscalls:sys_exit_sync",
+		"syscalls:sys_exit_sync_file_range",
+		"syscalls:sys_exit_fsync",
+		"syscalls:sys_exit_msync",
+	};
+	unsigned int disk_events_nr = ARRAY_SIZE(disk_events);
+
+	const char * const net_events[] = {
+		"syscalls:sys_enter_recvfrom",
+		"syscalls:sys_enter_recvmmsg",
+		"syscalls:sys_enter_recvmsg",
+		"syscalls:sys_enter_sendto",
+		"syscalls:sys_enter_sendmsg",
+		"syscalls:sys_enter_sendmmsg",
+
+		"syscalls:sys_exit_recvfrom",
+		"syscalls:sys_exit_recvmmsg",
+		"syscalls:sys_exit_recvmsg",
+		"syscalls:sys_exit_sendto",
+		"syscalls:sys_exit_sendmsg",
+		"syscalls:sys_exit_sendmmsg",
+	};
+	unsigned int net_events_nr = ARRAY_SIZE(net_events);
+
+	const char * const poll_events[] = {
+		"syscalls:sys_enter_epoll_pwait",
+		"syscalls:sys_enter_epoll_wait",
+		"syscalls:sys_enter_poll",
+		"syscalls:sys_enter_ppoll",
+		"syscalls:sys_enter_pselect6",
+		"syscalls:sys_enter_select",
+
+		"syscalls:sys_exit_epoll_pwait",
+		"syscalls:sys_exit_epoll_wait",
+		"syscalls:sys_exit_poll",
+		"syscalls:sys_exit_ppoll",
+		"syscalls:sys_exit_pselect6",
+		"syscalls:sys_exit_select",
+	};
+	unsigned int poll_events_nr = ARRAY_SIZE(poll_events);
+
+	rec_argc = common_args_nr +
+		disk_events_nr * 4 +
+		net_events_nr * 4 +
+		poll_events_nr * 4 +
+		argc;
+	rec_argv = calloc(rec_argc + 1, sizeof(char *));
+
+	if (rec_argv == NULL)
+		return -ENOMEM;
+
+	if (asprintf(&filter, "common_pid != %d", getpid()) < 0)
+		return -ENOMEM;
+
+	p = rec_argv;
+	for (i = 0; i < common_args_nr; i++)
+		*p++ = strdup(common_args[i]);
+
+	for (i = 0; i < disk_events_nr; i++) {
+		if (!is_valid_tracepoint(disk_events[i])) {
+			rec_argc -= 4;
+			continue;
+		}
+
+		*p++ = "-e";
+		*p++ = strdup(disk_events[i]);
+		*p++ = "--filter";
+		*p++ = filter;
+	}
+	for (i = 0; i < net_events_nr; i++) {
+		if (!is_valid_tracepoint(net_events[i])) {
+			rec_argc -= 4;
+			continue;
+		}
+
+		*p++ = "-e";
+		*p++ = strdup(net_events[i]);
+		*p++ = "--filter";
+		*p++ = filter;
+	}
+	for (i = 0; i < poll_events_nr; i++) {
+		if (!is_valid_tracepoint(poll_events[i])) {
+			rec_argc -= 4;
+			continue;
+		}
+
+		*p++ = "-e";
+		*p++ = strdup(poll_events[i]);
+		*p++ = "--filter";
+		*p++ = filter;
+	}
+
+	for (i = 0; i < (unsigned int)argc; i++)
+		*p++ = argv[i];
+
+	return cmd_record(rec_argc, rec_argv, NULL);
+}
+
+
 static int timechart__record(struct timechart *tchart, int argc, const char **argv)
 {
 	unsigned int rec_argc, i, j;
@@ -1314,6 +1893,8 @@ int cmd_timechart(int argc, const char **argv,
 	OPT_BOOLEAN('P', "power-only", &tchart.power_only, "output power data only"),
 	OPT_BOOLEAN('T', "tasks-only", &tchart.tasks_only,
 		    "output processes data only"),
+	OPT_BOOLEAN('I', "io-only", &tchart.io_only,
+		    "record only IO data"),
 	OPT_BOOLEAN('g', "callchain", &tchart.with_backtrace, "record callchain"),
 	OPT_END()
 	};
@@ -1340,7 +1921,10 @@ int cmd_timechart(int argc, const char **argv,
 			return -1;
 		}
 
-		return timechart__record(&tchart, argc, argv);
+		if (tchart.io_only)
+			return timechart__io_record(argc, argv);
+		else
+			return timechart__record(&tchart, argc, argv);
 	} else if (argc)
 		usage_with_options(timechart_usage, timechart_options);