[PATCH v2 1/1] perf stat: Add JSON output option.

Claire Jensen
2021-08-13T22:08:42Z

CSV output is tricky to format and column layout changes are susceptible
to breaking parsers. New JSON-formatted output has variable names to
identify fields that are consistent and informative, making
the output parseable.

CSV output example:

1.20,msec,task-clock:u,1204272,100.00,0.697,CPUs utilized
0,,context-switches:u,1204272,100.00,0.000,/sec
0,,cpu-migrations:u,1204272,100.00,0.000,/sec
70,,page-faults:u,1204272,100.00,58.126,K/sec

JSON output example:

{"counter-value" : "3805.723968", "unit" : "msec", "event" :
"cpu-clock", "event-runtime" : 3805731510100.00, "pcnt-running"
: 100.00, "metric-value" : 4.007571, "metric-unit" : "CPUs utilized"}
{"counter-value" : "6166.000000", "unit" : "", "event" :
"context-switches", "event-runtime" : 3805723045100.00, "pcnt-running"
: 100.00, "metric-value" : 1.620191, "metric-unit" : "K/sec"}
{"counter-value" : "466.000000", "unit" : "", "event" :
"cpu-migrations", "event-runtime" : 3805727613100.00, "pcnt-running"
: 100.00, "metric-value" : 122.447136, "metric-unit" : "/sec"}
{"counter-value" : "208.000000", "unit" : "", "event" :
"page-faults", "event-runtime" : 3805726799100.00, "pcnt-running"
: 100.00, "metric-value" : 54.654516, "metric-unit" : "/sec"}

Also added documentation for JSON option.

Version 2 includes change to SPDX-License-Identifier location, moving it
to line 3 due to an error when the test name was not found on
line 2. Additionally, testing was separated from the output patch.

Signed-off-by: Claire Jensen <cjense@google.com>
---
tools/perf/Documentation/perf-stat.txt | 21 ++
tools/perf/builtin-stat.c | 2 +
tools/perf/util/stat-display.c | 383 ++++++++++++++++++-------
tools/perf/util/stat-shadow.c | 5 +-
tools/perf/util/stat.h | 1 +
5 files changed, 310 insertions(+), 102 deletions(-)

diff --git a/tools/perf/Documentation/perf-stat.txt b/tools/perf/Documentation/perf-stat.txt
index 45c2467e4eb2..80ae3802a904 100644
--- a/tools/perf/Documentation/perf-stat.txt
+++ b/tools/perf/Documentation/perf-stat.txt
@@ -554,6 +554,27 @@ Additional metrics may be printed with all earlier fields being empty.

include::intel-hybrid.txt[]

+JSON FORMAT
+-----------
+
+With -j, perf stat is able to print out a JSON format output
+that can be used for parsing.
+
+- timestamp : optional usec time stamp in fractions of second (with -I)
+- optional aggregate options:
+ - core : core identifier (with --per-core)
+ - die : die identifier (with --per-die)
+ - socket : socket identifier (with --per-socket)
+ - node : node identifier (with --per-node)
+ - thread : thread identifier (with --per-thread)
+- counter-value : counter value
+- unit : unit of the counter value or empty
+- event : event name
+- variance : optional variance if multiple values are collected (with -r)
+- runtime : run time of counter
+- metric-value : optional metric value
+- metric-unit : optional unit of metric
+
SEE ALSO
--------
linkperf:perf-top[1], linkperf:perf-list[1]
diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 634375937db9..71b8418a2a06 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1218,6 +1218,8 @@ static struct option stat_options[] = {
OPT_BOOLEAN(0, "no-merge", &stat_config.no_merge, "Do not merge identical named events"),
OPT_STRING('x', "field-separator", &stat_config.csv_sep, "separator",
"print counts with custom separator"),
+ OPT_BOOLEAN('j', "json-output", &stat_config.json_output,
+ "print counts in JSON format"),
OPT_CALLBACK('G', "cgroup", &evsel_list, "name",
"monitor event in cgroup name only", parse_stat_cgroups),
OPT_STRING(0, "for-each-cgroup", &stat_config.cgroup_list, "name",
diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 588601000f3f..59de118352f3 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -27,23 +27,26 @@
static void print_running(struct perf_stat_config *config,
u64 run, u64 ena)
{
- if (config->csv_output) {
- fprintf(config->output, "%s%" PRIu64 "%s%.2f",
- config->csv_sep,
- run,
- config->csv_sep,
- ena ? 100.0 * run / ena : 100.0);
- } else if (run != ena) {
+ double enabled_percent = 100;
+ if (run != ena)
+ enabled_percent = 100 * run / ena;
+ if (config->json_output)
+ fprintf(config->output, "\"event-runtime\" : %lu, \"pcnt-running\" : %.2f, ",
+ run, enabled_percent);
+ else if (config->csv_output)
+ fprintf(config->output, "%s%" PRIu64 "%s%.2f", config->csv_sep,
+ run, config->csv_sep, enabled_percent);
+ else if (run != ena)
fprintf(config->output, " (%.2f%%)", 100.0 * run / ena);
- }
}

static void print_noise_pct(struct perf_stat_config *config,
double total, double avg)
{
double pct = rel_stddev_stats(total, avg);
-
- if (config->csv_output)
+ if (config->json_output)
+ fprintf(config->output, "\"variance\" : %.2f, ", pct);
+ else if (config->csv_output)
fprintf(config->output, "%s%.2f%%", config->csv_sep, pct);
else if (pct)
fprintf(config->output, " ( +-%6.2f%% )", pct);
@@ -63,9 +66,14 @@ static void print_noise(struct perf_stat_config *config,

static void print_cgroup(struct perf_stat_config *config, struct evsel *evsel)
{
- if (nr_cgroups) {
+ if (config->json_output && nr_cgroups) {
const char *cgrp_name = evsel->cgrp ? evsel->cgrp->name : "";
+ fprintf(config->output, "\"cgroup\" : \"%s\", ", cgrp_name);
+ } else {
+ if (nr_cgroups) {
+ const char *cgrp_name = evsel->cgrp ? evsel->cgrp->name : "";
fprintf(config->output, "%s%s", config->csv_sep, cgrp_name);
+ }
}
}

@@ -73,8 +81,18 @@ static void print_cgroup(struct perf_stat_config *config, struct evsel *evsel)
static void aggr_printout(struct perf_stat_config *config,
struct evsel *evsel, struct aggr_cpu_id id, int nr)
{
+ if (config->json_output && !config->interval)
+ fprintf(config->output, "{");
+
switch (config->aggr_mode) {
case AGGR_CORE:
+ if (config->json_output) {
+ fprintf(config->output, "\"core\" : \"S%d-D%d-C%d\", \"cpu\" : %d, ",
+ id.socket,
+ id.die,
+ id.core,
+ nr);
+ } else {
fprintf(config->output, "S%d-D%d-C%*d%s%*d%s",
id.socket,
id.die,
@@ -84,56 +102,95 @@ static void aggr_printout(struct perf_stat_config *config,
config->csv_output ? 0 : 4,
nr,
config->csv_sep);
+ }
break;
case AGGR_DIE:
- fprintf(config->output, "S%d-D%*d%s%*d%s",
- id.socket,
- config->csv_output ? 0 : -8,
- id.die,
- config->csv_sep,
- config->csv_output ? 0 : 4,
- nr,
- config->csv_sep);
+ if (config->json_output) {
+ fprintf(config->output, "\"die\" : \"S%d-D%d\", \"cpu\" : %d, ",
+ id.socket,
+ id.die,
+ nr);
+ } else {
+ fprintf(config->output, "S%d-D%*d%s%*d%s",
+ id.socket,
+ config->csv_output ? 0 : -8,
+ id.die,
+ config->csv_sep,
+ config->csv_output ? 0 : 4,
+ nr,
+ config->csv_sep);
+ }
break;
case AGGR_SOCKET:
- fprintf(config->output, "S%*d%s%*d%s",
- config->csv_output ? 0 : -5,
- id.socket,
- config->csv_sep,
- config->csv_output ? 0 : 4,
- nr,
- config->csv_sep);
+ if (config->json_output) {
+ fprintf(config->output, "\"socket\" : \"S%d\", \"number\" : %d, ",
+ id.socket,
+ nr);
+ } else {
+ fprintf(config->output, "S%*d%s%*d%s",
+ config->csv_output ? 0 : -5,
+ id.socket,
+ config->csv_sep,
+ config->csv_output ? 0 : 4,
+ nr,
+ config->csv_sep);
+ }
break;
case AGGR_NODE:
- fprintf(config->output, "N%*d%s%*d%s",
- config->csv_output ? 0 : -5,
- id.node,
- config->csv_sep,
- config->csv_output ? 0 : 4,
- nr,
- config->csv_sep);
+ if (config->json_output) {
+ fprintf(config->output, "\"node\" : \"N%d\", \"cpu\" : %d, ",
+ id.node,
+ nr);
+ } else {
+ fprintf(config->output, "N%*d%s%*d%s",
+ config->csv_output ? 0 : -5,
+ id.node,
+ config->csv_sep,
+ config->csv_output ? 0 : 4,
+ nr,
+ config->csv_sep);
+ }
break;
case AGGR_NONE:
- if (evsel->percore && !config->percore_show_thread) {
- fprintf(config->output, "S%d-D%d-C%*d%s",
- id.socket,
- id.die,
- config->csv_output ? 0 : -3,
- id.core, config->csv_sep);
+ if (config->json_output) {
+ if (evsel->percore && !config->percore_show_thread) {
+ fprintf(config->output, "\"core\" : \"S%d-D%d-C%d\"",
+ id.socket,
+ id.die,
+ id.core);
+ } else if (id.core > -1) {
+ fprintf(config->output, "\"cpu\" : \"%d\", ",
+ evsel__cpus(evsel)->map[id.core]);
+ }
+ } else {
+ if (evsel->percore && !config->percore_show_thread) {
+ fprintf(config->output, "S%d-D%d-C%*d%s",
+ id.socket,
+ id.die,
+ config->csv_output ? 0 : -3,
+ id.core, config->csv_sep);
} else if (id.core > -1) {
fprintf(config->output, "CPU%*d%s",
config->csv_output ? 0 : -7,
evsel__cpus(evsel)->map[id.core],
config->csv_sep);
- }
+ }
+ }
+
break;
case AGGR_THREAD:
- fprintf(config->output, "%*s-%*d%s",
- config->csv_output ? 0 : 16,
- perf_thread_map__comm(evsel->core.threads, id.thread),
- config->csv_output ? 0 : -8,
- perf_thread_map__pid(evsel->core.threads, id.thread),
- config->csv_sep);
+ if (config->json_output) {
+ fprintf(config->output, "\"thread\" : \"%s-%d\", ",
+ perf_thread_map__comm(evsel->core.threads, id.thread),
+ perf_thread_map__pid(evsel->core.threads, id.thread));
+ } else {
+ fprintf(config->output, "%*s-%*d%s",
+ config->csv_output ? 0 : 16,
+ perf_thread_map__comm(evsel->core.threads, id.thread),
+ config->csv_output ? 0 : -8,
+ perf_thread_map__pid(evsel->core.threads, id.thread),
+ config->csv_sep);
+ }
break;
case AGGR_GLOBAL:
case AGGR_UNSET:
@@ -184,20 +241,54 @@ static void print_metric_std(struct perf_stat_config *config,

os->newline = false;

+ if (unit == NULL || fmt == NULL) {
+ fprintf(out, "%-*s", METRIC_LEN, "");
+ return;
+ }
+ if (newline)
+ do_new_line_std(config, os);
+ n = fprintf(out, " # ");
+ if (color)
+ n += color_fprintf(out, color, fmt, val);
+ else
+ n += fprintf(out, fmt, val);
+ fprintf(out, " %-*s", METRIC_LEN - n - 1, unit);
+}
+
+static void print_metric_csv(struct perf_stat_config *config __maybe_unused,
+ void *ctx,
+ const char *color __maybe_unused,
+ const char *fmt, const char *unit, double val)
+{
+ struct outstate *os = ctx;
+ FILE *out = os->fh;
+ char buf[64], *vals, *ends;
+
if (unit == NULL || fmt == NULL) {
- fprintf(out, "%-*s", METRIC_LEN, "");
+ fprintf(out, "%s%s", config->csv_sep, config->csv_sep);
return;
}
+ snprintf(buf, sizeof(buf), fmt, val);
+ ends = vals = skip_spaces(buf);
+ while (isdigit(*ends) || *ends == '.')
+ ends++;
+ *ends = 0;
+ fprintf(out, "%s%s%s%s", config->csv_sep, vals,
+ config->csv_sep, skip_spaces(unit));
+}

- if (newline)
- do_new_line_std(config, os);
+static void print_metric_json(struct perf_stat_config *config __maybe_unused,
+ void *ctx,
+ const char *color __maybe_unused,
+ const char *fmt, const char *unit, double val)
+{
+ struct outstate *os = ctx;
+ FILE *out = os->fh;

- n = fprintf(out, " # ");
- if (color)
- n += color_fprintf(out, color, fmt, val);
- else
- n += fprintf(out, fmt, val);
- fprintf(out, " %-*s", METRIC_LEN - n - 1, unit);
+ fprintf(out, "\"metric-value\" : %f, ", val);
+ fprintf(out, "\"metric-unit\" : \"%s\"", unit);
+ if (!config->metric_only)
+ fprintf(out, "}");
}

static void new_line_csv(struct perf_stat_config *config, void *ctx)
@@ -213,25 +304,14 @@ static void new_line_csv(struct perf_stat_config *config, void *ctx)
fputs(config->csv_sep, os->fh);
}

-static void print_metric_csv(struct perf_stat_config *config __maybe_unused,
- void *ctx,
- const char *color __maybe_unused,
- const char *fmt, const char *unit, double val)
+static void new_line_json(struct perf_stat_config *config, void *ctx)
{
struct outstate *os = ctx;
- FILE *out = os->fh;
- char buf[64], *vals, *ends;

- if (unit == NULL || fmt == NULL) {
- fprintf(out, "%s%s", config->csv_sep, config->csv_sep);
- return;
- }
- snprintf(buf, sizeof(buf), fmt, val);
- ends = vals = skip_spaces(buf);
- while (isdigit(*ends) || *ends == '.')
- ends++;
- *ends = 0;
- fprintf(out, "%s%s%s%s", config->csv_sep, vals, config->csv_sep, skip_spaces(unit));
+ fputc('\n', os->fh);
+ if (os->prefix)
+ fprintf(os->fh, "%s", os->prefix);
+ aggr_printout(config, os->evsel, os->id, os->nr);
}

/* Filter out some columns that don't work well in metrics only mode */
@@ -292,7 +372,7 @@ static void print_metric_only_csv(struct perf_stat_config *config __maybe_unused
if (!valid_only_metric(unit))
return;
unit = fixunit(tbuf, os->evsel, unit);
- snprintf(buf, sizeof buf, fmt, val);
+ snprintf(buf, sizeof(buf), fmt, val);
ends = vals = skip_spaces(buf);
while (isdigit(*ends) || *ends == '.')
ends++;
@@ -300,6 +380,27 @@ static void print_metric_only_csv(struct perf_stat_config *config __maybe_unused
fprintf(out, "%s%s", vals, config->csv_sep);
}

+static void print_metric_only_json(struct perf_stat_config *config __maybe_unused,
+ void *ctx, const char *color __maybe_unused,
+ const char *fmt,
+ const char *unit, double val)
+{
+ struct outstate *os = ctx;
+ FILE *out = os->fh;
+ char buf[64], *vals, *ends;
+ char tbuf[1024];
+
+ if (!valid_only_metric(unit))
+ return;
+ unit = fixunit(tbuf, os->evsel, unit);
+ snprintf(buf, sizeof(buf), fmt, val);
+ ends = vals = skip_spaces(buf);
+ while (isdigit(*ends) || *ends == '.')
+ ends++;
+ *ends = 0;
+ fprintf(out, "{\"metric-value\" : \"%s\"}", vals);
+}
+
static void new_line_metric(struct perf_stat_config *config __maybe_unused,
void *ctx __maybe_unused)
{
@@ -318,10 +419,13 @@ static void print_metric_header(struct perf_stat_config *config,
os->evsel->priv != os->evsel->evlist->selected->priv)
return;

- if (!valid_only_metric(unit))
+ if (!valid_only_metric(unit) && !config->json_output)
return;
unit = fixunit(tbuf, os->evsel, unit);
- if (config->csv_output)
+
+ if (config->json_output)
+ fprintf(os->fh, "\"unit\" : \"%s\"", unit);
+ else if (config->csv_output)
fprintf(os->fh, "%s%s", unit, config->csv_sep);
else
fprintf(os->fh, "%*s ", config->metric_only_len, unit);
@@ -369,14 +473,27 @@ static void abs_printout(struct perf_stat_config *config,

aggr_printout(config, evsel, id, nr);

- fprintf(output, fmt, avg, config->csv_sep);
+ if (config->json_output)
+ fprintf(output, "\"counter-value\" : \"%f\", ", avg);
+ else
+ fprintf(output, fmt, avg, config->csv_sep);

- if (evsel->unit)
- fprintf(output, "%-*s%s",
- config->csv_output ? 0 : config->unit_width,
- evsel->unit, config->csv_sep);
+ if (config->json_output) {
+ if (evsel->unit) {
+ fprintf(output, "\"unit\" : \"%s\", ",
+ evsel->unit);
+ }
+ } else {
+ if (evsel->unit)
+ fprintf(output, "%-*s%s",
+ config->csv_output ? 0 : config->unit_width,
+ evsel->unit, config->csv_sep);
+ }

- fprintf(output, "%-*s", config->csv_output ? 0 : 25, evsel__name(evsel));
+ if (config->json_output)
+ fprintf(output, "\"event\" : \"%s\", ", evsel__name(evsel));
+ else
+ fprintf(output, "%-*s", config->csv_output ? 0 : 25, evsel__name(evsel));

print_cgroup(config, evsel);
}
@@ -425,6 +542,8 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
nl = new_line_metric;
if (config->csv_output)
pm = print_metric_only_csv;
+ else if (config->json_output)
+ pm = print_metric_only_json;
else
pm = print_metric_only;
} else
@@ -448,6 +567,24 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
os.nfields++;
}

+ if (config->json_output && !config->metric_only) {
+ static int aggr_fields[] = {
+ [AGGR_GLOBAL] = 0,
+ [AGGR_THREAD] = 1,
+ [AGGR_NONE] = 1,
+ [AGGR_SOCKET] = 2,
+ [AGGR_DIE] = 2,
+ [AGGR_CORE] = 2,
+ };
+
+ pm = print_metric_json;
+ nl = new_line_json;
+ os.nfields = 3;
+ os.nfields += aggr_fields[config->aggr_mode];
+ if (counter->cgrp)
+ os.nfields++;
+ }
+
if (!config->no_csv_summary && config->csv_output &&
config->summary && !config->interval) {
fprintf(config->output, "%16s%s", "summary", config->csv_sep);
@@ -460,10 +597,15 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
}
aggr_printout(config, counter, id, nr);

- fprintf(config->output, "%*s%s",
- config->csv_output ? 0 : 18,
- counter->supported ? CNTR_NOT_COUNTED : CNTR_NOT_SUPPORTED,
- config->csv_sep);
+ if (config->json_output) {
+ fprintf(config->output, "\"counter-value\" : \"%s\", ",
+ counter->supported ? CNTR_NOT_COUNTED : CNTR_NOT_SUPPORTED);
+ } else {
+ fprintf(config->output, "%*s%s",
+ config->csv_output ? 0 : 18,
+ counter->supported ? CNTR_NOT_COUNTED : CNTR_NOT_SUPPORTED,
+ config->csv_sep);
+ }

if (counter->supported) {
if (!evlist__has_hybrid(counter->evlist)) {
@@ -473,21 +615,32 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
}
}

- fprintf(config->output, "%-*s%s",
- config->csv_output ? 0 : config->unit_width,
- counter->unit, config->csv_sep);
+ if (config->json_output) {
+ fprintf(config->output, "\"unit\" : \"%s\", ", counter->unit);
+ } else {
+ fprintf(config->output, "%-*s%s",
+ config->csv_output ? 0 : config->unit_width,
+ counter->unit, config->csv_sep);
+ }

- fprintf(config->output, "%*s",
- config->csv_output ? 0 : -25, evsel__name(counter));
+ if (config->json_output) {
+ fprintf(config->output, "\"event\" : \"%s\", ",
+ evsel__name(counter));
+ } else {
+ fprintf(config->output, "%*s",
+ config->csv_output ? 0 : -25, evsel__name(counter));
+ }

print_cgroup(config, counter);

- if (!config->csv_output)
+ if (!config->csv_output && !config->json_output)
pm(config, &os, NULL, NULL, "", 0);
print_noise(config, counter, noise);
print_running(config, run, ena);
if (config->csv_output)
pm(config, &os, NULL, NULL, "", 0);
+ else if (config->json_output)
+ pm(config, &os, NULL, NULL, "", 0);
return;
}

@@ -502,12 +655,15 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
if (config->csv_output && !config->metric_only) {
print_noise(config, counter, noise);
print_running(config, run, ena);
+ } else if (config->json_output && !config->metric_only) {
+ print_noise(config, counter, noise);
+ print_running(config, run, ena);
}

perf_stat__print_shadow_stats(config, counter, uval,
first_shadow_cpu(config, counter, id),
&out, &config->metric_events, st);
- if (!config->csv_output && !config->metric_only) {
+ if (!config->csv_output && !config->metric_only && !config->json_output) {
print_noise(config, counter, noise);
print_running(config, run, ena);
}
@@ -866,7 +1022,8 @@ static void print_counter_aggr(struct perf_stat_config *config,
fprintf(output, "%s", prefix);

uval = cd.avg * counter->scale;
- printout(config, cpu_map__empty_aggr_cpu_id(), 0, counter, uval, prefix, cd.avg_running,
+ printout(config, cpu_map__empty_aggr_cpu_id(), 0, counter,
+ uval, prefix, cd.avg_running,
cd.avg_enabled, cd.avg, &rt_stat);
if (!metric_only)
fprintf(output, "\n");
@@ -981,8 +1138,12 @@ static void print_metric_headers(struct perf_stat_config *config,
struct outstate os = {
.fh = config->output
};
+ bool first = true;
+
+ if (config->json_output && !config->interval)
+ fprintf(config->output, "{");

- if (prefix)
+ if (prefix && !config->json_output)
fprintf(config->output, "%s", prefix);

if (!config->csv_output && !no_indent)
@@ -1002,6 +1163,9 @@ static void print_metric_headers(struct perf_stat_config *config,
os.evsel = counter;
out.ctx = &os;
out.print_metric = print_metric_header;
+ if (!first && config->json_output)
+ fprintf(config->output, ", ");
+ first = false;
out.new_line = new_line_metric;
out.force_header = true;
perf_stat__print_shadow_stats(config, counter, 0,
@@ -1010,6 +1174,8 @@ static void print_metric_headers(struct perf_stat_config *config,
&config->metric_events,
&rt_stat);
}
+ if (config->json_output)
+ fprintf(config->output, "}");
fputc('\n', config->output);
}

@@ -1025,10 +1191,18 @@ static void print_interval(struct perf_stat_config *config,
if (config->interval_clear)
puts(CONSOLE_CLEAR);

- if (!config->iostat_run)
- sprintf(prefix, "%6lu.%09lu%s", (unsigned long) ts->tv_sec, ts->tv_nsec, config->csv_sep);
-
- if ((num_print_interval == 0 && !config->csv_output) || config->interval_clear) {
+ if (!config->iostat_run && !config->json_output)
+ sprintf(prefix, "%6lu.%09lu%s", (unsigned long) ts->tv_sec,
+ ts->tv_nsec, config->csv_sep);
+ if (!config->iostat_run && config->json_output && !config->metric_only)
+ sprintf(prefix, "{\"interval\" : %lu.%09lu, ", (unsigned long)
+ ts->tv_sec, ts->tv_nsec);
+ if (!config->iostat_run && config->json_output && config->metric_only)
+ sprintf(prefix, "{\"interval\" : %lu.%09lu}", (unsigned long)
+ ts->tv_sec, ts->tv_nsec);
+
+ if ((num_print_interval == 0 && !config->csv_output && !config->json_output)
+ || config->interval_clear) {
switch (config->aggr_mode) {
case AGGR_NODE:
fprintf(output, "# time node cpus");
@@ -1072,8 +1246,14 @@ static void print_interval(struct perf_stat_config *config,
}
}

- if ((num_print_interval == 0 || config->interval_clear) && metric_only)
+ if ((num_print_interval == 0 || config->interval_clear)
+ && metric_only && !config->json_output)
+ print_metric_headers(config, evlist, " ", true);
+ if ((num_print_interval == 0 || config->interval_clear)
+ && metric_only && config->json_output) {
+ fprintf(output, "{");
print_metric_headers(config, evlist, " ", true);
+ }
if (++num_print_interval == 25)
num_print_interval = 0;
}
@@ -1087,7 +1267,7 @@ static void print_header(struct perf_stat_config *config,

fflush(stdout);

- if (!config->csv_output) {
+ if (!config->csv_output && !config->json_output) {
fprintf(output, "\n");
fprintf(output, " Performance counter stats for ");
if (_target->bpf_str)
@@ -1276,6 +1456,9 @@ void evlist__print_counters(struct evlist *evlist, struct perf_stat_config *conf
num_print_iv = 0;
if (config->aggr_mode == AGGR_GLOBAL && prefix && !config->iostat_run)
fprintf(config->output, "%s", prefix);
+
+ if (config->json_output && !config->metric_only)
+ fprintf(config->output, "}");
}

switch (config->aggr_mode) {
@@ -1319,7 +1502,7 @@ void evlist__print_counters(struct evlist *evlist, struct perf_stat_config *conf
break;
}

- if (!interval && !config->csv_output)
+ if (!interval && !config->csv_output && !config->json_output)
print_footer(config);

fflush(config->output);
diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index 34a7f5c1fff7..156302f8eaf6 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -981,8 +981,9 @@ void perf_stat__print_shadow_stats(struct perf_stat_config *config,
total = max(total, runtime_stat_avg(st,
STAT_STALLED_CYCLES_BACK,
cpu, &rsd));
-
- if (total && avg) {
+ // TODO: Refactor code to avoid errors in JSON output.
+ // !config->json_output is temporary workaround for JSON linter.
+ if (total && avg && !config->json_output) {
out->new_line(config, ctxp);
ratio = total / avg;
print_metric(config, ctxp, NULL, "%7.2f ",
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index 32c8527de347..2bde525e7630 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -117,6 +117,7 @@ struct perf_stat_config {
bool no_inherit;
bool identifier;
bool csv_output;
+ bool json_output;
bool interval_clear;
bool metric_only;
bool null_run;
--
2.33.0.rc1.237.g0d66db33f3-goog