diff mbox series

[IGT] tools/intel_gpu_top: Add support for stdout logging

Message ID 20190208102612.17217-1-tvrtko.ursulin@linux.intel.com (mailing list archive)
State New, archived
Headers show
Series [IGT] tools/intel_gpu_top: Add support for stdout logging | expand

Commit Message

Tvrtko Ursulin Feb. 8, 2019, 10:26 a.m. UTC
From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Two new output modes are added: listing of text data to standard out (-l
on the command line), and dumping of JSON formatted records (-J), also to
standard out.

The first mode is selected automatically when non-interactive standard out
is detected.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
References: https://bugs.freedesktop.org/show_bug.cgi?id=108689
Cc: Eero Tamminen <eero.t.tamminen@intel.com>
Cc: 3.14pi@ukr.net
---
 man/intel_gpu_top.rst |   9 +-
 tools/intel_gpu_top.c | 742 +++++++++++++++++++++++++++++++++++-------
 2 files changed, 630 insertions(+), 121 deletions(-)

Comments

Chris Wilson Feb. 8, 2019, 10:33 a.m. UTC | #1
Quoting Tvrtko Ursulin (2019-02-08 10:26:12)
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> 
> Two new output modes are added: listing of text data to standard out (-l
> on the command line), and dumping of JSON formatted records (-J), also to
> standard out.

Any chance of interactive with yaml^W json to file?
-Chris
Chris Wilson Feb. 8, 2019, 10:48 a.m. UTC | #2
Quoting Tvrtko Ursulin (2019-02-08 10:26:12)
> +static unsigned int json_indent_level;
> +
> +static const char *json_indent[] = {
> +       "",
> +       "\t",
> +       "\t\t",
> +       "\t\t\t",
> +       "\t\t\t\t",
> +       "\t\t\t\t\t",
> +};
> +
> +#define ARRAY_SIZE(arr) (sizeof(arr)/sizeof(arr[0]))
> +
> +static unsigned int json_prev_struct_members;
> +static unsigned int json_struct_members;
> +
> +static void
> +json_open_struct(const char *name)
> +{
> +       assert(json_indent_level < ARRAY_SIZE(json_indent));
> +
> +       json_prev_struct_members = json_struct_members;
> +       json_struct_members = 0;
> +
> +       if (name)
> +               printf("%s%s\"%s\": {\n",
> +                      json_prev_struct_members ? ",\n" : "",
> +                      json_indent[json_indent_level],
> +                      name);

"%*s", json_indent_level, "\t\t\t\t\t\t"

Ok, that seems to tally with what I expect the output to look like.

> +static unsigned int stdout_level;

Ah, stdout == plain old output.

> +static int
> +print_header(struct engines *engines, double t,
> +            int lines, int con_w, int con_h, bool *consumed)
> +{
> +       struct pmu_counter fake_pmu = {
> +               .present = true,
> +               .val.cur = 1,
> +       };
> +       struct cnt_item period_items[] = {
> +               { &fake_pmu, 0, 0, 1.0, 1.0, t * 1e3, "duration" },
> +               { NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "ms" },
> +               { },
> +       };
> +       struct cnt_group period_group = {
> +               .name = "period",
> +               .items = period_items,
> +       };
> +       struct cnt_item freq_items[] = {
> +               { &engines->freq_req, 4, 0, 1.0, t, 1, "requested", "req" },
> +               { &engines->freq_act, 4, 0, 1.0, t, 1, "actual", "act" },
> +               { NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "MHz" },
> +               { },
> +       };
> +       struct cnt_group freq_group = {
> +               .name = "frequency",
> +               .display_name = "Freq MHz",
> +               .items = freq_items,
> +       };
> +       struct cnt_item irq_items[] = {
> +               { &engines->irq, 8, 0, 1.0, t, 1, "count", "/s" },
> +               { NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "irq/s" },
> +               { },
> +       };
> +       struct cnt_group irq_group = {
> +               .name = "interrupts",
> +               .display_name = "IRQ",
> +               .items = irq_items,
> +       };
> +       struct cnt_item rc6_items[] = {
> +               { &engines->rc6, 3, 0, 1e9, t, 100, "value", "%" },
> +               { NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "%" },
> +               { },
> +       };
> +       struct cnt_group rc6_group = {
> +               .name = "rc6",
> +               .display_name = "RC6",
> +               .items = rc6_items,
> +       };
> +       struct cnt_item power_items[] = {
> +               { &engines->rapl, 4, 2, 1.0, t, engines->rapl_scale, "value",
> +                 "W" },
> +               { NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "W" },
> +               { },
> +       };
> +       struct cnt_group power_group = {
> +               .name = "power",
> +               .display_name = "Power",
> +               .items = power_items,
> +       };
> +       struct cnt_group *groups[] = {
> +               &period_group,
> +               &freq_group,
> +               &irq_group,
> +               &rc6_group,
> +               &power_group,
> +               NULL
> +       };
> +
> +       if (output_mode != JSON)
> +               memmove(&groups[0], &groups[1],
> +                       sizeof(groups) - sizeof(groups[0]));
> +
> +       pops->open_struct(NULL);
> +
> +       *consumed = print_groups(groups);
> +
> +       if (output_mode == INTERACTIVE) {
> +               printf("\033[H\033[J");
> +
> +               if (lines++ < con_h)
> +                       printf("intel-gpu-top - %s/%s MHz;  %s%% RC6; %s %s; %s irqs/s\n",
> +                              freq_items[1].buf, freq_items[0].buf,
> +                              rc6_items[0].buf, power_items[0].buf,
> +                              engines->rapl_unit,
> +                              irq_items[0].buf);

I would suggest a timestamp (time of day) if room.

Hang on, I don't recall seeing a timestamp amongst the output?

Looks very, very neat.
-Chris
Tvrtko Ursulin Feb. 8, 2019, 10:52 a.m. UTC | #3
On 08/02/2019 10:33, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-02-08 10:26:12)
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> Two new output modes are added: listing of text data to standard out (-l
>> on the command line), and dumping of JSON formatted records (-J), also to
>> standard out.
> 
> Any chance of interactive with yaml^W json to file?

If you cannot do with shell redirection then sure, it shouldn't be hard 
to add.

YAML, if it follows the same patterns as JSON, also should be easy like 
a handful of lines.

And the latter.. I need some feedback from the users on how they plan to 
use it. This implementation outputs records, but if you Ctrl-C-it you 
get the last incomplete. And you probably need to wrap everything in [ ] 
to make an array of these records.

Regards,

Tvrtko
Chris Wilson Feb. 8, 2019, 10:57 a.m. UTC | #4
Quoting Tvrtko Ursulin (2019-02-08 10:52:19)
> 
> On 08/02/2019 10:33, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2019-02-08 10:26:12)
> >> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> >>
> >> Two new output modes are added: listing of text data to standard out (-l
> >> on the command line), and dumping of JSON formatted records (-J), also to
> >> standard out.
> > 
> > Any chance of interactive with yaml^W json to file?
> 
> If you cannot do with shell redirection then sure, it shouldn't be hard 
> to add.
> 
> YAML, if it follows the same patterns as JSON, also should be easy like 
> a handful of lines.
> 
> And the latter.. I need some feedback from the users on how they plan to 
> use it. This implementation outputs records, but if you Ctrl-C-it you 
> get the last incomplete. And you probably need to wrap everything in [ ] 
> to make an array of these records.

signal(SIGINT, close_output) ?
-Chris
Tvrtko Ursulin Feb. 8, 2019, 11:06 a.m. UTC | #5
On 08/02/2019 10:57, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-02-08 10:52:19)
>>
>> On 08/02/2019 10:33, Chris Wilson wrote:
>>> Quoting Tvrtko Ursulin (2019-02-08 10:26:12)
>>>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>>>
>>>> Two new output modes are added: listing of text data to standard out (-l
>>>> on the command line), and dumping of JSON formatted records (-J), also to
>>>> standard out.
>>>
>>> Any chance of interactive with yaml^W json to file?
>>
>> If you cannot do with shell redirection then sure, it shouldn't be hard
>> to add.
>>
>> YAML, if it follows the same patterns as JSON, also should be easy like
>> a handful of lines.
>>
>> And the latter.. I need some feedback from the users on how they plan to
>> use it. This implementation outputs records, but if you Ctrl-C-it you
>> get the last incomplete. And you probably need to wrap everything in [ ]
>> to make an array of these records.
> 
> signal(SIGINT, close_output) ?

I guess.. wanted to keep it simple but this is probably warranted.

Regards,

Tvrtko
diff mbox series

Patch

diff --git a/man/intel_gpu_top.rst b/man/intel_gpu_top.rst
index 19c712307d28..d5bda093c8e8 100644
--- a/man/intel_gpu_top.rst
+++ b/man/intel_gpu_top.rst
@@ -7,9 +7,9 @@  Display a top-like summary of Intel GPU usage
 ---------------------------------------------
 .. include:: defs.rst
 :Author: IGT Developers <igt-dev@lists.freedesktop.org>
-:Date: 2018-04-04
+:Date: 2019-02-08
 :Version: |PACKAGE_STRING|
-:Copyright: 2009,2011,2012,2016,2018 Intel Corporation
+:Copyright: 2009,2011,2012,2016,2018,2019 Intel Corporation
 :Manual section: |MANUAL_SECTION|
 :Manual group: |MANUAL_GROUP|
 
@@ -31,6 +31,11 @@  OPTIONS
 -s <ms>
     Refresh period in milliseconds.
 
+-l
+    List text data to standard out.
+
+-J
+    Output JSON formatted data to standard output.
 -h
     Show help text.
 
diff --git a/tools/intel_gpu_top.c b/tools/intel_gpu_top.c
index b923c3cfbe97..1313e0d46b5e 100644
--- a/tools/intel_gpu_top.c
+++ b/tools/intel_gpu_top.c
@@ -1,5 +1,5 @@ 
 /*
- * Copyright © 2007-2018 Intel Corporation
+ * Copyright © 2007-2019 Intel Corporation
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
@@ -19,10 +19,6 @@ 
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  * DEALINGS IN THE SOFTWARE.
- *
- * Authors:
- *    Eric Anholt <eric@anholt.net>
- *    Eugeni Dodonov <eugeni.dodonov@intel.com>
  */
 
 #include <stdio.h>
@@ -41,6 +37,7 @@ 
 #include <errno.h>
 #include <math.h>
 #include <locale.h>
+#include <limits.h>
 
 #include "igt_perf.h"
 
@@ -59,6 +56,7 @@  struct pmu_counter {
 struct engine {
 	const char *name;
 	const char *display_name;
+	const char *short_name;
 
 	unsigned int class;
 	unsigned int instance;
@@ -142,6 +140,22 @@  static const char *class_display_name(unsigned int class)
 	}
 }
 
+static const char *class_short_name(unsigned int class)
+{
+	switch (class) {
+	case I915_ENGINE_CLASS_RENDER:
+		return "RCS";
+	case I915_ENGINE_CLASS_COPY:
+		return "BCS";
+	case I915_ENGINE_CLASS_VIDEO:
+		return "VCS";
+	case I915_ENGINE_CLASS_VIDEO_ENHANCE:
+		return "VECS";
+	default:
+		return "UNKN";
+	}
+}
+
 static int engine_cmp(const void *__a, const void *__b)
 {
 	const struct engine *a = (struct engine *)__a;
@@ -227,7 +241,6 @@  static struct engines *discover_engines(void)
 			ret = ENOBUFS;
 			break;
 		}
-		ret = 0;
 
 		engine->display_name = strdup(buf);
 		if (!engine->display_name) {
@@ -235,6 +248,20 @@  static struct engines *discover_engines(void)
 			break;
 		}
 
+		ret = snprintf(buf, sizeof(buf), "%s/%u",
+			       class_short_name(engine->class),
+			       engine->instance);
+		if (ret < 0 || ret == sizeof(buf)) {
+			ret = ENOBUFS;
+			break;
+		}
+
+		engine->short_name = strdup(buf);
+		if (!engine->short_name) {
+			ret = errno;
+			break;
+		}
+
 		engines->num_engines++;
 		engines = realloc(engines, sizeof(struct engines) +
 				  engines->num_engines * sizeof(struct engine));
@@ -242,6 +269,8 @@  static struct engines *discover_engines(void)
 			ret = errno;
 			break;
 		}
+
+		ret = 0;
 	}
 
 	if (ret) {
@@ -551,7 +580,7 @@  static uint64_t pmu_read_multi(int fd, unsigned int num, uint64_t *val)
 	return buf[1];
 }
 
-static double __pmu_calc(struct pmu_pair *p, double d, double t, double s)
+static double pmu_calc(struct pmu_pair *p, double d, double t, double s)
 {
 	double v;
 
@@ -576,30 +605,6 @@  static void fill_str(char *buf, unsigned int bufsz, char c, unsigned int num)
 	*buf = 0;
 }
 
-static void pmu_calc(struct pmu_counter *cnt,
-		     char *buf, unsigned int bufsz,
-		     unsigned int width, unsigned width_dec,
-		     double d, double t, double s)
-{
-	double val;
-	int len;
-
-	assert(bufsz >= (width + width_dec + 1));
-
-	if (!cnt->present) {
-		fill_str(buf, bufsz, '-', width + width_dec);
-		return;
-	}
-
-	val = __pmu_calc(&cnt->val, d, t, s);
-
-	len = snprintf(buf, bufsz, "%*.*f", width + width_dec, width_dec, val);
-	if (len < 0 || len == bufsz) {
-		fill_str(buf, bufsz, 'X', width + width_dec);
-		return;
-	}
-}
-
 static uint64_t __pmu_read_single(int fd, uint64_t *ts)
 {
 	uint64_t data[2] = { };
@@ -697,11 +702,552 @@  usage(const char *appname)
 		"\n"
 		"\tThe following parameters are optional:\n\n"
 		"\t[-s <ms>]       Refresh period in milliseconds (default %ums).\n"
+		"\t[-l]            List data to standard out.\n"
+		"\t[-J]            JSON data to standard out.\n"
 		"\t[-h]            Show this help text.\n"
 		"\n",
 		appname, DEFAULT_PERIOD_MS);
 }
 
+static enum {
+	INTERACTIVE,
+	STDOUT,
+	JSON
+} output_mode;
+
+struct cnt_item {
+	struct pmu_counter *pmu;
+	unsigned int fmt_d;
+	unsigned int fmt_dd;
+	double d;
+	double t;
+	double s;
+	const char *name;
+	const char *unit;
+
+	/* Internal fields. */
+	char buf[16];
+};
+
+struct cnt_group {
+	const char *name;
+	const char *display_name;
+	struct cnt_item *items;
+};
+
+static unsigned int json_indent_level;
+
+static const char *json_indent[] = {
+	"",
+	"\t",
+	"\t\t",
+	"\t\t\t",
+	"\t\t\t\t",
+	"\t\t\t\t\t",
+};
+
+#define ARRAY_SIZE(arr) (sizeof(arr)/sizeof(arr[0]))
+
+static unsigned int json_prev_struct_members;
+static unsigned int json_struct_members;
+
+static void
+json_open_struct(const char *name)
+{
+	assert(json_indent_level < ARRAY_SIZE(json_indent));
+
+	json_prev_struct_members = json_struct_members;
+	json_struct_members = 0;
+
+	if (name)
+		printf("%s%s\"%s\": {\n",
+		       json_prev_struct_members ? ",\n" : "",
+		       json_indent[json_indent_level],
+		       name);
+	else
+		printf("%s\n%s{\n",
+		       json_prev_struct_members ? "," : "",
+		       json_indent[json_indent_level]);
+
+	json_indent_level++;
+}
+
+static void
+json_close_struct(void)
+{
+	assert(json_indent_level > 0);
+
+	printf("\n%s}", json_indent[--json_indent_level]);
+
+	if (json_indent_level == 0)
+		fflush(stdout);
+}
+
+static unsigned int
+json_add_member(const struct cnt_group *parent, struct cnt_item *item,
+		unsigned int headers)
+{
+	assert(json_indent_level < ARRAY_SIZE(json_indent));
+
+	printf("%s%s\"%s\": ",
+		json_struct_members ? ",\n" : "",
+		json_indent[json_indent_level], item->name);
+
+	json_struct_members++;
+
+	if (!strcmp(item->name, "unit"))
+		printf("\"%s\"", item->unit);
+	else
+		printf("%f",
+		       pmu_calc(&item->pmu->val, item->d, item->t, item->s));
+
+	return 1;
+}
+
+static unsigned int stdout_level;
+
+#define STDOUT_HEADER_REPEAT 20
+static unsigned int stdout_lines = STDOUT_HEADER_REPEAT;
+
+static void
+stdout_open_struct(const char *name)
+{
+	stdout_level++;
+	assert(stdout_level > 0);
+}
+
+static void
+stdout_close_struct(void)
+{
+	assert(stdout_level > 0);
+	if (--stdout_level == 0) {
+		stdout_lines++;
+		printf("\n");
+		fflush(stdout);
+	}
+}
+
+static unsigned int
+stdout_add_member(const struct cnt_group *parent, struct cnt_item *item,
+		  unsigned int headers)
+{
+	unsigned int fmt_tot = item->fmt_d + (item->fmt_dd ? 1 : 0);
+	char buf[fmt_tot + 1];
+	double val;
+	int len;
+
+	if (!item->pmu)
+		return 0;
+	else if (!item->pmu->present)
+		return 0;
+
+	if (headers == 1) {
+		unsigned int grp_tot = 0;
+		struct cnt_item *it;
+
+		if (item != parent->items)
+			return 0;
+
+		for (it = parent->items; it->pmu; it++) {
+			if (!it->pmu->present)
+				continue;
+
+			grp_tot += 1 + it->fmt_d + (it->fmt_dd ? 1 : 0);
+		}
+
+		printf("%*s ", grp_tot - 1, parent->display_name);
+		return 0;
+	} else if (headers == 2) {
+		printf("%*s ", fmt_tot, item->unit ?: item->name);
+		return 0;
+	}
+
+	val = pmu_calc(&item->pmu->val, item->d, item->t, item->s);
+
+	len = snprintf(buf, sizeof(buf), "%*.*f", fmt_tot, item->fmt_dd, val);
+	if (len < 0 || len == sizeof(buf))
+		fill_str(buf, sizeof(buf), 'X', fmt_tot);
+
+	len = printf("%s ", buf);
+
+	return len > 0 ? len : 0;
+}
+
+static void
+term_open_struct(const char *name)
+{
+}
+
+static void
+term_close_struct(void)
+{
+}
+
+static unsigned int
+term_add_member(const struct cnt_group *parent, struct cnt_item *item,
+		unsigned int headers)
+{
+	unsigned int fmt_tot = item->fmt_d + (item->fmt_dd ? 1 : 0);
+	double val;
+	int len;
+
+	if (!item->pmu)
+		return 0;
+
+	assert(fmt_tot <= sizeof(item->buf));
+
+	if (!item->pmu->present) {
+		fill_str(item->buf, sizeof(item->buf), '-', fmt_tot);
+		return 1;
+	}
+
+	val = pmu_calc(&item->pmu->val, item->d, item->t, item->s);
+	len = snprintf(item->buf, sizeof(item->buf),
+		       "%*.*f",
+		       fmt_tot, item->fmt_dd, val);
+
+	if (len < 0 || len == sizeof(item->buf))
+		fill_str(item->buf, sizeof(item->buf), 'X', fmt_tot);
+
+	return 1;
+}
+
+struct print_operations {
+	void (*open_struct)(const char *name);
+	void (*close_struct)(void);
+	unsigned int (*add_member)(const struct cnt_group *parent,
+				   struct cnt_item *item,
+				   unsigned int headers);
+	bool (*print_group)(struct cnt_group *group, unsigned int headers);
+};
+
+static const struct print_operations *pops;
+
+static unsigned int
+present_in_group(const struct cnt_group *grp)
+{
+	unsigned int present = 0;
+	struct cnt_item *item;
+
+	for (item = grp->items; item->name; item++) {
+		if (item->pmu && item->pmu->present)
+			present++;
+	}
+
+	return present;
+}
+
+static bool
+print_group(struct cnt_group *grp, unsigned int headers)
+{
+	unsigned int consumed = 0;
+	struct cnt_item *item;
+
+	if (!present_in_group(grp))
+		return false;
+
+	pops->open_struct(grp->name);
+
+	for (item = grp->items; item->name; item++)
+		consumed += pops->add_member(grp, item, headers);
+
+	pops->close_struct();
+
+	return consumed;
+}
+
+static bool
+term_print_group(struct cnt_group *grp, unsigned int headers)
+{
+	unsigned int consumed = 0;
+	struct cnt_item *item;
+
+	pops->open_struct(grp->name);
+
+	for (item = grp->items; item->name; item++)
+		consumed += pops->add_member(grp, item, headers);
+
+	pops->close_struct();
+
+	return consumed;
+}
+
+static const struct print_operations json_pops = {
+	.open_struct = json_open_struct,
+	.close_struct = json_close_struct,
+	.add_member = json_add_member,
+	.print_group = print_group,
+};
+
+static const struct print_operations stdout_pops = {
+	.open_struct = stdout_open_struct,
+	.close_struct = stdout_close_struct,
+	.add_member = stdout_add_member,
+	.print_group = print_group,
+};
+
+static const struct print_operations term_pops = {
+	.open_struct = term_open_struct,
+	.close_struct = term_close_struct,
+	.add_member = term_add_member,
+	.print_group = term_print_group,
+};
+
+static bool print_groups(struct cnt_group **groups)
+{
+	unsigned int headers = stdout_lines % STDOUT_HEADER_REPEAT + 1;
+	bool print_data = true;
+
+	if (output_mode == STDOUT && (headers == 1 || headers == 2)) {
+		for (struct cnt_group **grp = groups; *grp; grp++)
+			print_data = pops->print_group(*grp, headers);
+	}
+
+	for (struct cnt_group **grp = groups; print_data && *grp; grp++)
+		pops->print_group(*grp, false);
+
+	return print_data;
+}
+
+static int
+print_header(struct engines *engines, double t,
+	     int lines, int con_w, int con_h, bool *consumed)
+{
+	struct pmu_counter fake_pmu = {
+		.present = true,
+		.val.cur = 1,
+	};
+	struct cnt_item period_items[] = {
+		{ &fake_pmu, 0, 0, 1.0, 1.0, t * 1e3, "duration" },
+		{ NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "ms" },
+		{ },
+	};
+	struct cnt_group period_group = {
+		.name = "period",
+		.items = period_items,
+	};
+	struct cnt_item freq_items[] = {
+		{ &engines->freq_req, 4, 0, 1.0, t, 1, "requested", "req" },
+		{ &engines->freq_act, 4, 0, 1.0, t, 1, "actual", "act" },
+		{ NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "MHz" },
+		{ },
+	};
+	struct cnt_group freq_group = {
+		.name = "frequency",
+		.display_name = "Freq MHz",
+		.items = freq_items,
+	};
+	struct cnt_item irq_items[] = {
+		{ &engines->irq, 8, 0, 1.0, t, 1, "count", "/s" },
+		{ NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "irq/s" },
+		{ },
+	};
+	struct cnt_group irq_group = {
+		.name = "interrupts",
+		.display_name = "IRQ",
+		.items = irq_items,
+	};
+	struct cnt_item rc6_items[] = {
+		{ &engines->rc6, 3, 0, 1e9, t, 100, "value", "%" },
+		{ NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "%" },
+		{ },
+	};
+	struct cnt_group rc6_group = {
+		.name = "rc6",
+		.display_name = "RC6",
+		.items = rc6_items,
+	};
+	struct cnt_item power_items[] = {
+		{ &engines->rapl, 4, 2, 1.0, t, engines->rapl_scale, "value",
+		  "W" },
+		{ NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "W" },
+		{ },
+	};
+	struct cnt_group power_group = {
+		.name = "power",
+		.display_name = "Power",
+		.items = power_items,
+	};
+	struct cnt_group *groups[] = {
+		&period_group,
+		&freq_group,
+		&irq_group,
+		&rc6_group,
+		&power_group,
+		NULL
+	};
+
+	if (output_mode != JSON)
+		memmove(&groups[0], &groups[1],
+			sizeof(groups) - sizeof(groups[0]));
+
+	pops->open_struct(NULL);
+
+	*consumed = print_groups(groups);
+
+	if (output_mode == INTERACTIVE) {
+		printf("\033[H\033[J");
+
+		if (lines++ < con_h)
+			printf("intel-gpu-top - %s/%s MHz;  %s%% RC6; %s %s; %s irqs/s\n",
+			       freq_items[1].buf, freq_items[0].buf,
+			       rc6_items[0].buf, power_items[0].buf,
+			       engines->rapl_unit,
+			       irq_items[0].buf);
+
+		if (lines++ < con_h)
+			printf("\n");
+	}
+
+	return lines;
+}
+
+static int
+print_imc(struct engines *engines, double t, int lines, int con_w, int con_h)
+{
+	struct cnt_item imc_items[] = {
+		{ &engines->imc_reads, 6, 0, 1.0, t, engines->imc_reads_scale,
+		  "reads", "rd" },
+		{ &engines->imc_writes, 6, 0, 1.0, t, engines->imc_writes_scale,
+		  "writes", "wr" },
+		{ NULL, 0, 0, 0.0, 0.0, 0.0, "unit" },
+		{ },
+	};
+	struct cnt_group imc_group = {
+		.name = "imc-bandwidth",
+		.items = imc_items,
+	};
+	struct cnt_group *groups[] = {
+		&imc_group,
+		NULL
+	};
+	int ret;
+
+	ret = asprintf((char **)&imc_group.display_name, "IMC %s/s",
+			engines->imc_reads_unit);
+	assert(ret >= 0);
+
+	ret = asprintf((char **)&imc_items[2].unit, "%s/s",
+			engines->imc_reads_unit);
+	assert(ret >= 0);
+
+	print_groups(groups);
+
+	free((void *)imc_group.display_name);
+	free((void *)imc_items[2].unit);
+
+	if (output_mode == INTERACTIVE) {
+		if (lines++ < con_h)
+			printf("      IMC reads:   %s %s/s\n",
+			       imc_items[0].buf, engines->imc_reads_unit);
+
+		if (lines++ < con_h)
+			printf("     IMC writes:   %s %s/s\n",
+			       imc_items[1].buf, engines->imc_writes_unit);
+
+		if (lines++ < con_h)
+			printf("\n");
+	}
+
+	return lines;
+}
+
+static int
+print_engines_header(struct engines *engines, double t,
+		     int lines, int con_w, int con_h)
+{
+	for (unsigned int i = 0;
+	     i < engines->num_engines && lines < con_h;
+	     i++) {
+		struct engine *engine = engine_ptr(engines, i);
+
+		if (!engine->num_counters)
+			continue;
+
+		pops->open_struct("engines");
+
+		if (output_mode == INTERACTIVE) {
+			const char *a = "          ENGINE      BUSY ";
+			const char *b = " MI_SEMA MI_WAIT";
+
+			printf("\033[7m%s%*s%s\033[0m\n",
+			       a, (int)(con_w - 1 - strlen(a) - strlen(b)),
+			       " ", b);
+
+			lines++;
+		}
+
+		break;
+	}
+
+	return lines;
+}
+
+static int
+print_engine(struct engines *engines, unsigned int i, double t,
+	     int lines, int con_w, int con_h)
+{
+	struct engine *engine = engine_ptr(engines, i);
+	struct cnt_item engine_items[] = {
+		{ &engine->busy, 6, 2, 1e9, t, 100, "busy", "%" },
+		{ &engine->sema, 3, 0, 1e9, t, 100, "sema", "se" },
+		{ &engine->wait, 3, 0, 1e9, t, 100, "wait", "wa" },
+		{ NULL, 0, 0, 0.0, 0.0, 0.0, "unit", "%" },
+		{ },
+	};
+	struct cnt_group engine_group = {
+		.name = engine->display_name,
+		.display_name = engine->short_name,
+		.items = engine_items,
+	};
+	struct cnt_group *groups[] = {
+		&engine_group,
+		NULL
+	};
+
+	if (!engine->num_counters)
+		return lines;
+
+	print_groups(groups);
+
+	if (output_mode == INTERACTIVE) {
+		unsigned int max_w = con_w - 1;
+		unsigned int len;
+		char buf[128];
+		double val;
+
+		len = snprintf(buf, sizeof(buf), "    %s%%    %s%%",
+			       engine_items[1].buf, engine_items[2].buf);
+
+		len += printf("%16s %s%% ",
+			      engine->display_name, engine_items[0].buf);
+
+		val = pmu_calc(&engine->busy.val, 1e9, t, 100);
+		print_percentage_bar(val, max_w - len);
+
+		printf("%s\n", buf);
+
+		lines++;
+	}
+
+	return lines;
+}
+
+static int
+print_engines_footer(struct engines *engines, double t,
+		     int lines, int con_w, int con_h)
+{
+	pops->close_struct();
+	pops->close_struct();
+
+	if (output_mode == INTERACTIVE) {
+		if (lines++ < con_h)
+			printf("\n");
+	}
+
+	return lines;
+}
+
 int main(int argc, char **argv)
 {
 	unsigned int period_us = DEFAULT_PERIOD_MS * 1000;
@@ -711,11 +1257,17 @@  int main(int argc, char **argv)
 	int ret, ch;
 
 	/* Parse options */
-	while ((ch = getopt(argc, argv, "s:h")) != -1) {
+	while ((ch = getopt(argc, argv, "s:Jlh")) != -1) {
 		switch (ch) {
 		case 's':
 			period_us = atoi(optarg) * 1000;
 			break;
+		case 'J':
+			output_mode = JSON;
+			break;
+		case 'l':
+			output_mode = STDOUT;
+			break;
 		case 'h':
 			usage(argv[0]);
 			exit(0);
@@ -726,6 +1278,24 @@  int main(int argc, char **argv)
 		}
 	}
 
+	if (output_mode == INTERACTIVE && isatty(1) != 1)
+		output_mode = STDOUT;
+
+	switch (output_mode) {
+	case INTERACTIVE:
+		pops = &term_pops;
+		break;
+	case STDOUT:
+		pops = &stdout_pops;
+		break;
+	case JSON:
+		pops = &json_pops;
+		break;
+	default:
+		assert(0);
+		break;
+	};
+
 	engines = discover_engines();
 	if (!engines) {
 		fprintf(stderr,
@@ -744,20 +1314,15 @@  int main(int argc, char **argv)
 	pmu_sample(engines);
 
 	for (;;) {
-		double t;
-#define BUFSZ 16
-		char freq[BUFSZ];
-		char fact[BUFSZ];
-		char irq[BUFSZ];
-		char rc6[BUFSZ];
-		char power[BUFSZ];
-		char reads[BUFSZ];
-		char writes[BUFSZ];
-		struct winsize ws;
+		bool consumed = false;
 		int lines = 0;
+		struct winsize ws;
+		double t;
 
 		/* Update terminal size. */
-		if (ioctl(0, TIOCGWINSZ, &ws) != -1) {
+		if (output_mode != INTERACTIVE) {
+			con_w = con_h = INT_MAX;
+		} else if (ioctl(0, TIOCGWINSZ, &ws) != -1) {
 			con_w = ws.ws_col;
 			con_h = ws.ws_row;
 		}
@@ -765,88 +1330,27 @@  int main(int argc, char **argv)
 		pmu_sample(engines);
 		t = (double)(engines->ts.cur - engines->ts.prev) / 1e9;
 
-		printf("\033[H\033[J");
-
-		pmu_calc(&engines->freq_req, freq, BUFSZ, 4, 0, 1.0, t, 1);
-		pmu_calc(&engines->freq_act, fact, BUFSZ, 4, 0, 1.0, t, 1);
-		pmu_calc(&engines->irq, irq, BUFSZ, 8, 0, 1.0, t, 1);
-		pmu_calc(&engines->rc6, rc6, BUFSZ, 3, 0, 1e9, t, 100);
-		pmu_calc(&engines->rapl, power, BUFSZ, 4, 2, 1.0, t,
-			 engines->rapl_scale);
-		pmu_calc(&engines->imc_reads, reads, BUFSZ, 6, 0, 1.0, t,
-			 engines->imc_reads_scale);
-		pmu_calc(&engines->imc_writes, writes, BUFSZ, 6, 0, 1.0, t,
-			 engines->imc_writes_scale);
-
-		if (lines++ < con_h)
-			printf("intel-gpu-top - %s/%s MHz;  %s%% RC6; %s %s; %s irqs/s\n",
-			       fact, freq, rc6, power, engines->rapl_unit, irq);
+		while (!consumed) {
+			lines = print_header(engines, t, lines, con_w, con_h,
+					     &consumed);
 
-		if (lines++ < con_h)
-			printf("\n");
+			if (engines->imc_fd)
+				lines = print_imc(engines, t, lines, con_w,
+						  con_h);
 
-		if (engines->imc_fd) {
-			if (lines++ < con_h)
-				printf("      IMC reads:   %s %s/s\n",
-				       reads, engines->imc_reads_unit);
+			lines = print_engines_header(engines, t, lines, con_w,
+						     con_h);
 
-			if (lines++ < con_h)
-				printf("     IMC writes:   %s %s/s\n",
-				       writes, engines->imc_writes_unit);
+			for (i = 0;
+			     i < engines->num_engines && lines < con_h;
+			     i++)
+				lines = print_engine(engines, i, t, lines,
+						     con_w, con_h);
 
-			if (++lines < con_h)
-				printf("\n");
+			lines = print_engines_footer(engines, t, lines, con_w,
+						     con_h);
 		}
 
-		for (i = 0; i < engines->num_engines; i++) {
-			struct engine *engine = engine_ptr(engines, i);
-
-			if (engine->num_counters && lines < con_h) {
-				const char *a = "          ENGINE      BUSY ";
-				const char *b = " MI_SEMA MI_WAIT";
-
-				printf("\033[7m%s%*s%s\033[0m\n",
-				       a,
-				       (int)(con_w - 1 - strlen(a) - strlen(b)),
-				       " ", b);
-				lines++;
-				break;
-			}
-		}
-
-		for (i = 0; i < engines->num_engines && lines < con_h; i++) {
-			struct engine *engine = engine_ptr(engines, i);
-			unsigned int max_w = con_w - 1;
-			unsigned int len;
-			char sema[BUFSZ];
-			char wait[BUFSZ];
-			char busy[BUFSZ];
-			char buf[128];
-			double val;
-
-			if (!engine->num_counters)
-				continue;
-
-			pmu_calc(&engine->sema, sema, BUFSZ, 3, 0, 1e9, t, 100);
-			pmu_calc(&engine->wait, wait, BUFSZ, 3, 0, 1e9, t, 100);
-			len = snprintf(buf, sizeof(buf), "    %s%%    %s%%",
-				       sema, wait);
-
-			pmu_calc(&engine->busy, busy, BUFSZ, 6, 2, 1e9, t,
-				 100);
-			len += printf("%16s %s%% ", engine->display_name, busy);
-
-			val = __pmu_calc(&engine->busy.val, 1e9, t, 100);
-			print_percentage_bar(val, max_w - len);
-
-			printf("%s\n", buf);
-
-			lines++;
-		}
-
-		if (lines++ < con_h)
-			printf("\n");
-
 		usleep(period_us);
 	}