[PATCH 0/2] perf stat: Fix trailing comma when there is no metric unit

[PATCH 0/2] perf stat: Fix trailing comma when there is no metric unit

[James Clark]

The first commit is failing on Arm and I think the fix should stop more
trailing comma issues which keep happening.

The second one I just noticed when looking at it. I don't feel strongly
about it so not sure if we should do it or not, but seems like the
empty metric exclusion from the JSON should be consistent if we're going
to have it at all.

James Clark (2):
  perf stat: Fix trailing comma when there is no metric unit
  perf stat: Also hide metric from JSON if units are an empty string

 .../tests/shell/lib/perf_json_output_lint.py  |  14 +-
 tools/perf/util/stat-display.c                | 179 ++++++++++--------
 2 files changed, 105 insertions(+), 88 deletions(-)

-- 
2.34.1

[PATCH 1/2] perf stat: Fix trailing comma when there is no metric unit

[James Clark]

Now that printing metric-value and metric-unit is optional,
print_running_json() shouldn't add the comma in case it becomes
trailing.

Replace all manual json comma stuff with a json_out() function that uses
the existing os->first tracking and auto inserts a comma if it's needed.
Update the test to handle that two of the fields can be missing.

This fixes the following test failure on Cortex A57 where the branch
misses metric is missing a required event:

 $ perf test -vvv "json output"

 106: perf stat JSON output linter:
 --- start ---
 test child forked, pid 665682
 Checking json output: no args Test failed for input:
 ...
 {"counter-value" : "3112.000000", "unit" : "",
  "event" : "armv8_pmuv3_1/branch-misses/",
  "event-runtime" : 20699340, "pcnt-running" : 100.00, }
 ...
 json.decoder.JSONDecodeError: Expecting property name enclosed in
 double quotes: line 12 column 144 (char 2109)
 ---- end(-1) ----
 106: perf stat JSON output linter                 : FAILED!

Fixes: e1cc918b6cfd ("perf stat: Drop metric-unit if unit is NULL")
Signed-off-by: James Clark <james.clark@linaro.org>
---
 .../tests/shell/lib/perf_json_output_lint.py  |  14 +-
 tools/perf/util/stat-display.c                | 177 ++++++++++--------
 2 files changed, 104 insertions(+), 87 deletions(-)

diff --git a/tools/perf/tests/shell/lib/perf_json_output_lint.py b/tools/perf/tests/shell/lib/perf_json_output_lint.py
index 8ddb85586131..b066d721f897 100644
--- a/tools/perf/tests/shell/lib/perf_json_output_lint.py
+++ b/tools/perf/tests/shell/lib/perf_json_output_lint.py
@@ -69,16 +69,16 @@ def check_json_output(expected_items):
   for item in json.loads(input):
     if expected_items != -1:
       count = len(item)
-      if count != expected_items and count >= 1 and count <= 7 and 'metric-value' in item:
+      if count not in expected_items and count >= 1 and count <= 7 and 'metric-value' in item:
         # Events that generate >1 metric may have isolated metric
         # values and possibly other prefixes like interval, core,
         # aggregate-number, or event-runtime/pcnt-running from multiplexing.
         pass
-      elif count != expected_items and count >= 1 and count <= 5 and 'metricgroup' in item:
+      elif count not in expected_items and count >= 1 and count <= 5 and 'metricgroup' in item:
         pass
-      elif count == expected_items + 1 and 'metric-threshold' in item:
+      elif count - 1 in expected_items and 'metric-threshold' in item:
           pass
-      elif count != expected_items:
+      elif count not in expected_items:
         raise RuntimeError(f'wrong number of fields. counted {count} expected {expected_items}'
                            f' in \'{item}\'')
     for key, value in item.items():
@@ -90,11 +90,11 @@ def check_json_output(expected_items):
 
 try:
   if args.no_args or args.system_wide or args.event:
-    expected_items = 7
+    expected_items = [5, 7]
   elif args.interval or args.per_thread or args.system_wide_no_aggr:
-    expected_items = 8
+    expected_items = [6, 8]
   elif args.per_core or args.per_socket or args.per_node or args.per_die or args.per_cluster or args.per_cache:
-    expected_items = 9
+    expected_items = [7, 9]
   else:
     # If no option is specified, don't check the number of items.
     expected_items = -1
diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index 53dcdf07f5a2..a5d72f4a515c 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -114,23 +114,44 @@ static void print_running_csv(struct perf_stat_config *config, u64 run, u64 ena)
 	fprintf(config->output, "%s%" PRIu64 "%s%.2f",
 		config->csv_sep, run, config->csv_sep, enabled_percent);
 }
+struct outstate {
+	FILE *fh;
+	bool newline;
+	bool first;
+	const char *prefix;
+	int  nfields;
+	int  aggr_nr;
+	struct aggr_cpu_id id;
+	struct evsel *evsel;
+	struct cgroup *cgrp;
+};
 
-static void print_running_json(struct perf_stat_config *config, u64 run, u64 ena)
+static const char *json_sep(struct outstate *os)
+{
+	const char *sep = os->first ? "" : ", ";
+
+	os->first = false;
+	return sep;
+}
+
+#define json_out(os, format, ...) fprintf((os)->fh, "%s" format, json_sep(os), ##__VA_ARGS__)
+
+static void print_running_json(struct outstate *os, u64 run, u64 ena)
 {
 	double enabled_percent = 100;
 
 	if (run != ena)
 		enabled_percent = 100 * run / ena;
-	fprintf(config->output, "\"event-runtime\" : %" PRIu64 ", \"pcnt-running\" : %.2f, ",
-		run, enabled_percent);
+	json_out(os, "\"event-runtime\" : %" PRIu64 ", \"pcnt-running\" : %.2f",
+		 run, enabled_percent);
 }
 
-static void print_running(struct perf_stat_config *config,
+static void print_running(struct perf_stat_config *config, struct outstate *os,
 			  u64 run, u64 ena, bool before_metric)
 {
 	if (config->json_output) {
 		if (before_metric)
-			print_running_json(config, run, ena);
+			print_running_json(os, run, ena);
 	} else if (config->csv_output) {
 		if (before_metric)
 			print_running_csv(config, run, ena);
@@ -153,20 +174,20 @@ static void print_noise_pct_csv(struct perf_stat_config *config,
 	fprintf(config->output, "%s%.2f%%", config->csv_sep, pct);
 }
 
-static void print_noise_pct_json(struct perf_stat_config *config,
+static void print_noise_pct_json(struct outstate *os,
 				 double pct)
 {
-	fprintf(config->output, "\"variance\" : %.2f, ", pct);
+	json_out(os, "\"variance\" : %.2f", pct);
 }
 
-static void print_noise_pct(struct perf_stat_config *config,
+static void print_noise_pct(struct perf_stat_config *config, struct outstate *os,
 			    double total, double avg, bool before_metric)
 {
 	double pct = rel_stddev_stats(total, avg);
 
 	if (config->json_output) {
 		if (before_metric)
-			print_noise_pct_json(config, pct);
+			print_noise_pct_json(os, pct);
 	} else if (config->csv_output) {
 		if (before_metric)
 			print_noise_pct_csv(config, pct);
@@ -176,7 +197,7 @@ static void print_noise_pct(struct perf_stat_config *config,
 	}
 }
 
-static void print_noise(struct perf_stat_config *config,
+static void print_noise(struct perf_stat_config *config, struct outstate *os,
 			struct evsel *evsel, double avg, bool before_metric)
 {
 	struct perf_stat_evsel *ps;
@@ -185,7 +206,7 @@ static void print_noise(struct perf_stat_config *config,
 		return;
 
 	ps = evsel->stats;
-	print_noise_pct(config, stddev_stats(&ps->res_stats), avg, before_metric);
+	print_noise_pct(config, os, stddev_stats(&ps->res_stats), avg, before_metric);
 }
 
 static void print_cgroup_std(struct perf_stat_config *config, const char *cgrp_name)
@@ -198,18 +219,19 @@ static void print_cgroup_csv(struct perf_stat_config *config, const char *cgrp_n
 	fprintf(config->output, "%s%s", config->csv_sep, cgrp_name);
 }
 
-static void print_cgroup_json(struct perf_stat_config *config, const char *cgrp_name)
+static void print_cgroup_json(struct outstate *os, const char *cgrp_name)
 {
-	fprintf(config->output, "\"cgroup\" : \"%s\", ", cgrp_name);
+	json_out(os, "\"cgroup\" : \"%s\"", cgrp_name);
 }
 
-static void print_cgroup(struct perf_stat_config *config, struct cgroup *cgrp)
+static void print_cgroup(struct perf_stat_config *config, struct outstate *os,
+			 struct cgroup *cgrp)
 {
 	if (nr_cgroups || config->cgroup_list) {
 		const char *cgrp_name = cgrp ? cgrp->name  : "";
 
 		if (config->json_output)
-			print_cgroup_json(config, cgrp_name);
+			print_cgroup_json(os, cgrp_name);
 		else if (config->csv_output)
 			print_cgroup_csv(config, cgrp_name);
 		else
@@ -324,47 +346,45 @@ static void print_aggr_id_csv(struct perf_stat_config *config,
 	}
 }
 
-static void print_aggr_id_json(struct perf_stat_config *config,
+static void print_aggr_id_json(struct perf_stat_config *config, struct outstate *os,
 			       struct evsel *evsel, struct aggr_cpu_id id, int aggr_nr)
 {
-	FILE *output = config->output;
-
 	switch (config->aggr_mode) {
 	case AGGR_CORE:
-		fprintf(output, "\"core\" : \"S%d-D%d-C%d\", \"aggregate-number\" : %d, ",
+		json_out(os, "\"core\" : \"S%d-D%d-C%d\", \"aggregate-number\" : %d",
 			id.socket, id.die, id.core, aggr_nr);
 		break;
 	case AGGR_CACHE:
-		fprintf(output, "\"cache\" : \"S%d-D%d-L%d-ID%d\", \"aggregate-number\" : %d, ",
+		json_out(os, "\"cache\" : \"S%d-D%d-L%d-ID%d\", \"aggregate-number\" : %d",
 			id.socket, id.die, id.cache_lvl, id.cache, aggr_nr);
 		break;
 	case AGGR_CLUSTER:
-		fprintf(output, "\"cluster\" : \"S%d-D%d-CLS%d\", \"aggregate-number\" : %d, ",
+		json_out(os, "\"cluster\" : \"S%d-D%d-CLS%d\", \"aggregate-number\" : %d",
 			id.socket, id.die, id.cluster, aggr_nr);
 		break;
 	case AGGR_DIE:
-		fprintf(output, "\"die\" : \"S%d-D%d\", \"aggregate-number\" : %d, ",
+		json_out(os, "\"die\" : \"S%d-D%d\", \"aggregate-number\" : %d",
 			id.socket, id.die, aggr_nr);
 		break;
 	case AGGR_SOCKET:
-		fprintf(output, "\"socket\" : \"S%d\", \"aggregate-number\" : %d, ",
+		json_out(os, "\"socket\" : \"S%d\", \"aggregate-number\" : %d",
 			id.socket, aggr_nr);
 		break;
 	case AGGR_NODE:
-		fprintf(output, "\"node\" : \"N%d\", \"aggregate-number\" : %d, ",
+		json_out(os, "\"node\" : \"N%d\", \"aggregate-number\" : %d",
 			id.node, aggr_nr);
 		break;
 	case AGGR_NONE:
 		if (evsel->percore && !config->percore_show_thread) {
-			fprintf(output, "\"core\" : \"S%d-D%d-C%d\"",
+			json_out(os, "\"core\" : \"S%d-D%d-C%d\"",
 				id.socket, id.die, id.core);
 		} else if (id.cpu.cpu > -1) {
-			fprintf(output, "\"cpu\" : \"%d\", ",
+			json_out(os, "\"cpu\" : \"%d\"",
 				id.cpu.cpu);
 		}
 		break;
 	case AGGR_THREAD:
-		fprintf(output, "\"thread\" : \"%s-%d\", ",
+		json_out(os, "\"thread\" : \"%s-%d\"",
 			perf_thread_map__comm(evsel->core.threads, id.thread_idx),
 			perf_thread_map__pid(evsel->core.threads, id.thread_idx));
 		break;
@@ -376,29 +396,17 @@ static void print_aggr_id_json(struct perf_stat_config *config,
 	}
 }
 
-static void aggr_printout(struct perf_stat_config *config,
+static void aggr_printout(struct perf_stat_config *config, struct outstate *os,
 			  struct evsel *evsel, struct aggr_cpu_id id, int aggr_nr)
 {
 	if (config->json_output)
-		print_aggr_id_json(config, evsel, id, aggr_nr);
+		print_aggr_id_json(config, os, evsel, id, aggr_nr);
 	else if (config->csv_output)
 		print_aggr_id_csv(config, evsel, id, aggr_nr);
 	else
 		print_aggr_id_std(config, evsel, id, aggr_nr);
 }
 
-struct outstate {
-	FILE *fh;
-	bool newline;
-	bool first;
-	const char *prefix;
-	int  nfields;
-	int  aggr_nr;
-	struct aggr_cpu_id id;
-	struct evsel *evsel;
-	struct cgroup *cgrp;
-};
-
 static void new_line_std(struct perf_stat_config *config __maybe_unused,
 			 void *ctx)
 {
@@ -413,7 +421,7 @@ static inline void __new_line_std_csv(struct perf_stat_config *config,
 	fputc('\n', os->fh);
 	if (os->prefix)
 		fputs(os->prefix, os->fh);
-	aggr_printout(config, os->evsel, os->id, os->aggr_nr);
+	aggr_printout(config, os, os->evsel, os->id, os->aggr_nr);
 }
 
 static inline void __new_line_std(struct outstate *os)
@@ -499,9 +507,9 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
 	FILE *out = os->fh;
 
 	if (unit) {
-		fprintf(out, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
+		json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
 		if (thresh != METRIC_THRESHOLD_UNKNOWN) {
-			fprintf(out, ", \"metric-threshold\" : \"%s\"",
+			json_out(os, "\"metric-threshold\" : \"%s\"",
 				metric_threshold_classify__str(thresh));
 		}
 	}
@@ -514,9 +522,11 @@ static void new_line_json(struct perf_stat_config *config, void *ctx)
 	struct outstate *os = ctx;
 
 	fputs("\n{", os->fh);
+	os->first = true;
 	if (os->prefix)
-		fprintf(os->fh, "%s", os->prefix);
-	aggr_printout(config, os->evsel, os->id, os->aggr_nr);
+		json_out(os, "%s", os->prefix);
+
+	aggr_printout(config, os, os->evsel, os->id, os->aggr_nr);
 }
 
 static void print_metricgroup_header_json(struct perf_stat_config *config,
@@ -526,7 +536,7 @@ static void print_metricgroup_header_json(struct perf_stat_config *config,
 	if (!metricgroup_name)
 		return;
 
-	fprintf(config->output, "\"metricgroup\" : \"%s\"}", metricgroup_name);
+	json_out((struct outstate *) ctx, "\"metricgroup\" : \"%s\"}", metricgroup_name);
 	new_line_json(config, ctx);
 }
 
@@ -644,7 +654,6 @@ static void print_metric_only_json(struct perf_stat_config *config __maybe_unuse
 				  const char *unit, double val)
 {
 	struct outstate *os = ctx;
-	FILE *out = os->fh;
 	char buf[64], *ends;
 	char tbuf[1024];
 	const char *vals;
@@ -661,8 +670,7 @@ static void print_metric_only_json(struct perf_stat_config *config __maybe_unuse
 	*ends = 0;
 	if (!vals[0])
 		vals = "none";
-	fprintf(out, "%s\"%s\" : \"%s\"", os->first ? "" : ", ", unit, vals);
-	os->first = false;
+	json_out(os, "\"%s\" : \"%s\"", unit, vals);
 }
 
 static void new_line_metric(struct perf_stat_config *config __maybe_unused,
@@ -743,28 +751,27 @@ static void print_counter_value_csv(struct perf_stat_config *config,
 	fprintf(output, "%s", evsel__name(evsel));
 }
 
-static void print_counter_value_json(struct perf_stat_config *config,
+static void print_counter_value_json(struct outstate *os,
 				     struct evsel *evsel, double avg, bool ok)
 {
-	FILE *output = config->output;
 	const char *bad_count = evsel->supported ? CNTR_NOT_COUNTED : CNTR_NOT_SUPPORTED;
 
 	if (ok)
-		fprintf(output, "\"counter-value\" : \"%f\", ", avg);
+		json_out(os, "\"counter-value\" : \"%f\"", avg);
 	else
-		fprintf(output, "\"counter-value\" : \"%s\", ", bad_count);
+		json_out(os, "\"counter-value\" : \"%s\"", bad_count);
 
 	if (evsel->unit)
-		fprintf(output, "\"unit\" : \"%s\", ", evsel->unit);
+		json_out(os, "\"unit\" : \"%s\"", evsel->unit);
 
-	fprintf(output, "\"event\" : \"%s\", ", evsel__name(evsel));
+	json_out(os, "\"event\" : \"%s\"", evsel__name(evsel));
 }
 
-static void print_counter_value(struct perf_stat_config *config,
+static void print_counter_value(struct perf_stat_config *config, struct outstate *os,
 				struct evsel *evsel, double avg, bool ok)
 {
 	if (config->json_output)
-		print_counter_value_json(config, evsel, avg, ok);
+		print_counter_value_json(os, evsel, avg, ok);
 	else if (config->csv_output)
 		print_counter_value_csv(config, evsel, avg, ok);
 	else
@@ -772,12 +779,13 @@ static void print_counter_value(struct perf_stat_config *config,
 }
 
 static void abs_printout(struct perf_stat_config *config,
+			 struct outstate *os,
 			 struct aggr_cpu_id id, int aggr_nr,
 			 struct evsel *evsel, double avg, bool ok)
 {
-	aggr_printout(config, evsel, id, aggr_nr);
-	print_counter_value(config, evsel, avg, ok);
-	print_cgroup(config, evsel->cgrp);
+	aggr_printout(config, os, evsel, id, aggr_nr);
+	print_counter_value(config, os, evsel, avg, ok);
+	print_cgroup(config, os, evsel->cgrp);
 }
 
 static bool is_mixed_hw_group(struct evsel *counter)
@@ -868,17 +876,17 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
 	out.force_header = false;
 
 	if (!config->metric_only && !counter->default_metricgroup) {
-		abs_printout(config, os->id, os->aggr_nr, counter, uval, ok);
+		abs_printout(config, os, os->id, os->aggr_nr, counter, uval, ok);
 
-		print_noise(config, counter, noise, /*before_metric=*/true);
-		print_running(config, run, ena, /*before_metric=*/true);
+		print_noise(config, os, counter, noise, /*before_metric=*/true);
+		print_running(config, os, run, ena, /*before_metric=*/true);
 	}
 
 	if (ok) {
 		if (!config->metric_only && counter->default_metricgroup) {
 			void *from = NULL;
 
-			aggr_printout(config, os->evsel, os->id, os->aggr_nr);
+			aggr_printout(config, os, os->evsel, os->id, os->aggr_nr);
 			/* Print out all the metricgroup with the same metric event. */
 			do {
 				int num = 0;
@@ -891,8 +899,8 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
 						__new_line_std_csv(config, os);
 				}
 
-				print_noise(config, counter, noise, /*before_metric=*/true);
-				print_running(config, run, ena, /*before_metric=*/true);
+				print_noise(config, os, counter, noise, /*before_metric=*/true);
+				print_running(config, os, run, ena, /*before_metric=*/true);
 				from = perf_stat__print_shadow_stats_metricgroup(config, counter, aggr_idx,
 										 &num, from, &out,
 										 &config->metric_events);
@@ -905,8 +913,8 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
 	}
 
 	if (!config->metric_only) {
-		print_noise(config, counter, noise, /*before_metric=*/false);
-		print_running(config, run, ena, /*before_metric=*/false);
+		print_noise(config, os, counter, noise, /*before_metric=*/false);
+		print_running(config, os, run, ena, /*before_metric=*/false);
 	}
 }
 
@@ -1083,12 +1091,17 @@ static void print_counter_aggrdata(struct perf_stat_config *config,
 		return;
 
 	if (!metric_only) {
-		if (config->json_output)
+		if (config->json_output) {
+			os->first = true;
 			fputc('{', output);
-		if (os->prefix)
-			fprintf(output, "%s", os->prefix);
-		else if (config->summary && config->csv_output &&
-			 !config->no_csv_summary && !config->interval)
+		}
+		if (os->prefix) {
+			if (config->json_output)
+				json_out(os, "%s", os->prefix);
+			else
+				fprintf(output, "%s", os->prefix);
+		} else if (config->summary && config->csv_output &&
+			   !config->no_csv_summary && !config->interval)
 			fprintf(output, "%s%s", "summary", config->csv_sep);
 	}
 
@@ -1114,15 +1127,19 @@ static void print_metric_begin(struct perf_stat_config *config,
 
 	if (config->json_output)
 		fputc('{', config->output);
-	if (os->prefix)
-		fprintf(config->output, "%s", os->prefix);
 
+	if (os->prefix) {
+		if (config->json_output)
+			json_out(os, "%s", os->prefix);
+		else
+			fprintf(config->output, "%s", os->prefix);
+	}
 	evsel = evlist__first(evlist);
 	id = config->aggr_map->map[aggr_idx];
 	aggr = &evsel->stats->aggr[aggr_idx];
-	aggr_printout(config, evsel, id, aggr->nr);
+	aggr_printout(config, os, evsel, id, aggr->nr);
 
-	print_cgroup(config, os->cgrp ? : evsel->cgrp);
+	print_cgroup(config, os, os->cgrp ? : evsel->cgrp);
 }
 
 static void print_metric_end(struct perf_stat_config *config, struct outstate *os)
@@ -1343,7 +1360,7 @@ static void prepare_interval(struct perf_stat_config *config,
 		return;
 
 	if (config->json_output)
-		scnprintf(prefix, len, "\"interval\" : %lu.%09lu, ",
+		scnprintf(prefix, len, "\"interval\" : %lu.%09lu",
 			  (unsigned long) ts->tv_sec, ts->tv_nsec);
 	else if (config->csv_output)
 		scnprintf(prefix, len, "%lu.%09lu%s",
@@ -1557,7 +1574,7 @@ static void print_footer(struct perf_stat_config *config)
 		fprintf(output, " %17.*f +- %.*f seconds time elapsed",
 			precision, avg, precision, sd);
 
-		print_noise_pct(config, sd, avg, /*before_metric=*/false);
+		print_noise_pct(config, NULL, sd, avg, /*before_metric=*/false);
 	}
 	fprintf(output, "\n\n");
 
-- 
2.34.1

[PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

[James Clark]

We decided to hide NULL metric units rather than showing it as "(null)",
but on hybrid systems if the process doesn't hit a PMU you get an empty
string metric unit instead. To make it consistent also remove empty
strings.

Note that metric-threshold is already hidden in this case without this
change.

Where a process only runs on cpu_core and never hits cpu_atom:
Before:
 $ perf stat -j -- true
 ...
 {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
 {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
 ...

After:
 ...
 {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
 {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
 ...

Signed-off-by: James Clark <james.clark@linaro.org>
---
 tools/perf/util/stat-display.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index a5d72f4a515c..9b7fd985a42a 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
 	struct outstate *os = ctx;
 	FILE *out = os->fh;
 
-	if (unit) {
+	if (unit && strlen(unit)) {
 		json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
 		if (thresh != METRIC_THRESHOLD_UNKNOWN) {
 			json_out(os, "\"metric-threshold\" : \"%s\"",
-- 
2.34.1

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

[Namhyung Kim]

Hello,

On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
> We decided to hide NULL metric units rather than showing it as "(null)",
> but on hybrid systems if the process doesn't hit a PMU you get an empty
> string metric unit instead. To make it consistent also remove empty
> strings.
> 
> Note that metric-threshold is already hidden in this case without this
> change.
> 
> Where a process only runs on cpu_core and never hits cpu_atom:
> Before:
>  $ perf stat -j -- true
>  ...
>  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
>  {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>  ...

I guess you're talking about "metric-unit", not plain "unit", right?
Then please update the subject line to reduce the config.

Ian, can you please review?

Thanks,
Namhyung

> 
> After:
>  ...
>  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
>  {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>  ...
> 
> Signed-off-by: James Clark <james.clark@linaro.org>
> ---
>  tools/perf/util/stat-display.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> index a5d72f4a515c..9b7fd985a42a 100644
> --- a/tools/perf/util/stat-display.c
> +++ b/tools/perf/util/stat-display.c
> @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
>  	struct outstate *os = ctx;
>  	FILE *out = os->fh;
>  
> -	if (unit) {
> +	if (unit && strlen(unit)) {
>  		json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
>  		if (thresh != METRIC_THRESHOLD_UNKNOWN) {
>  			json_out(os, "\"metric-threshold\" : \"%s\"",
> -- 
> 2.34.1
> 

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

[Ian Rogers]

On Tue, Oct 29, 2024 at 5:42 PM Namhyung Kim <namhyung@kernel.org> wrote:
>
> Hello,
>
> On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
> > We decided to hide NULL metric units rather than showing it as "(null)",
> > but on hybrid systems if the process doesn't hit a PMU you get an empty
> > string metric unit instead. To make it consistent also remove empty
> > strings.
> >
> > Note that metric-threshold is already hidden in this case without this
> > change.
> >
> > Where a process only runs on cpu_core and never hits cpu_atom:
> > Before:
> >  $ perf stat -j -- true
> >  ...
> >  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
> >  {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >  ...
>
> I guess you're talking about "metric-unit", not plain "unit", right?
> Then please update the subject line to reduce the config.
>
> Ian, can you please review?

It'd be nice to see the stack trace for when metric-unit is "" as I'm
not seeing the logic in stat-shadow.c. If we know the caller than it
seems logical the unit can be passed as NULL rather than "".

Thanks,
Ian

> Thanks,
> Namhyung
>
> >
> > After:
> >  ...
> >  {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
> >  {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >  ...
> >
> > Signed-off-by: James Clark <james.clark@linaro.org>
> > ---
> >  tools/perf/util/stat-display.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> > index a5d72f4a515c..9b7fd985a42a 100644
> > --- a/tools/perf/util/stat-display.c
> > +++ b/tools/perf/util/stat-display.c
> > @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
> >       struct outstate *os = ctx;
> >       FILE *out = os->fh;
> >
> > -     if (unit) {
> > +     if (unit && strlen(unit)) {
> >               json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
> >               if (thresh != METRIC_THRESHOLD_UNKNOWN) {
> >                       json_out(os, "\"metric-threshold\" : \"%s\"",
> > --
> > 2.34.1
> >

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

[James Clark]

On 30/10/2024 2:45 am, Ian Rogers wrote:
> On Tue, Oct 29, 2024 at 5:42 PM Namhyung Kim <namhyung@kernel.org> wrote:
>>
>> Hello,
>>
>> On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
>>> We decided to hide NULL metric units rather than showing it as "(null)",
>>> but on hybrid systems if the process doesn't hit a PMU you get an empty
>>> string metric unit instead. To make it consistent also remove empty
>>> strings.
>>>
>>> Note that metric-threshold is already hidden in this case without this
>>> change.
>>>
>>> Where a process only runs on cpu_core and never hits cpu_atom:
>>> Before:
>>>   $ perf stat -j -- true
>>>   ...
>>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
>>>   {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>>>   ...
>>
>> I guess you're talking about "metric-unit", not plain "unit", right?
>> Then please update the subject line to reduce the config.
>>

Yep I'll update it.

>> Ian, can you please review?
> 
> It'd be nice to see the stack trace for when metric-unit is "" as I'm
> not seeing the logic in stat-shadow.c. If we know the caller than it
> seems logical the unit can be passed as NULL rather than "".
> 
> Thanks,
> Ian
> 


Here's the stack:

print_metric_json() (stat-display.c:516)
printout() (stat-display.c:912)
print_counter_aggrdata() (stat-display.c:1110)
print_counter() (stat-display.c:1224)
evlist__print_counters() (stat-display.c:1734)
print_counters() (builtin-stat.c:1016)
cmd_stat() (builtin-stat.c:2872)
run_builtin() (perf/perf.c:351)
handle_internal_command() (perf.c:404)
run_argv() (perf.c:448)
main() (perf.c:560)

The empty string is from printout():

   pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/"",
      /*val=*/0);

Changing it to NULL seems to work, so is probably a bit neater. I can do 
that if you think that makes sense?

There's another one for --metric-only that I didn't run into, but it 
could also make sense to change:

   if (config->metric_only) {
     pm(config, os, METRIC_THRESHOLD_UNKNOWN, "", "", 0);

>> Thanks,
>> Namhyung
>>
>>>
>>> After:
>>>   ...
>>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
>>>   {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
>>>   ...
>>>
>>> Signed-off-by: James Clark <james.clark@linaro.org>
>>> ---
>>>   tools/perf/util/stat-display.c | 2 +-
>>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
>>> index a5d72f4a515c..9b7fd985a42a 100644
>>> --- a/tools/perf/util/stat-display.c
>>> +++ b/tools/perf/util/stat-display.c
>>> @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
>>>        struct outstate *os = ctx;
>>>        FILE *out = os->fh;
>>>
>>> -     if (unit) {
>>> +     if (unit && strlen(unit)) {
>>>                json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
>>>                if (thresh != METRIC_THRESHOLD_UNKNOWN) {
>>>                        json_out(os, "\"metric-threshold\" : \"%s\"",
>>> --
>>> 2.34.1
>>>

Re: [PATCH 2/2] perf stat: Also hide metric from JSON if units are an empty string

[Ian Rogers]

On Wed, Oct 30, 2024 at 2:36 AM James Clark <james.clark@linaro.org> wrote:
>
>
>
> On 30/10/2024 2:45 am, Ian Rogers wrote:
> > On Tue, Oct 29, 2024 at 5:42 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >>
> >> Hello,
> >>
> >> On Fri, Oct 25, 2024 at 10:03:05AM +0100, James Clark wrote:
> >>> We decided to hide NULL metric units rather than showing it as "(null)",
> >>> but on hybrid systems if the process doesn't hit a PMU you get an empty
> >>> string metric unit instead. To make it consistent also remove empty
> >>> strings.
> >>>
> >>> Note that metric-threshold is already hidden in this case without this
> >>> change.
> >>>
> >>> Where a process only runs on cpu_core and never hits cpu_atom:
> >>> Before:
> >>>   $ perf stat -j -- true
> >>>   ...
> >>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00, "metric-value" : "0.000000", "metric-unit" : ""}
> >>>   {"counter-value" : "6326.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 293786, "pcnt-running" : 100.00, "metric-value" : "3.553394", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >>>   ...
> >>
> >> I guess you're talking about "metric-unit", not plain "unit", right?
> >> Then please update the subject line to reduce the config.
> >>
>
> Yep I'll update it.
>
> >> Ian, can you please review?
> >
> > It'd be nice to see the stack trace for when metric-unit is "" as I'm
> > not seeing the logic in stat-shadow.c. If we know the caller than it
> > seems logical the unit can be passed as NULL rather than "".
> >
> > Thanks,
> > Ian
> >
>
>
> Here's the stack:
>
> print_metric_json() (stat-display.c:516)
> printout() (stat-display.c:912)
> print_counter_aggrdata() (stat-display.c:1110)
> print_counter() (stat-display.c:1224)
> evlist__print_counters() (stat-display.c:1734)
> print_counters() (builtin-stat.c:1016)
> cmd_stat() (builtin-stat.c:2872)
> run_builtin() (perf/perf.c:351)
> handle_internal_command() (perf.c:404)
> run_argv() (perf.c:448)
> main() (perf.c:560)
>
> The empty string is from printout():
>
>    pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/"",
>       /*val=*/0);
>
> Changing it to NULL seems to work, so is probably a bit neater. I can do
> that if you think that makes sense?
>
> There's another one for --metric-only that I didn't run into, but it
> could also make sense to change:
>
>    if (config->metric_only) {
>      pm(config, os, METRIC_THRESHOLD_UNKNOWN, "", "", 0);

Yeah, it looks like all the callers should be passing NULL. I feel
more comfortable doing this than ignoring the empty string which is
something a json metric may accidentally do. Could you send a patch?

Thanks,
Ian

> >> Thanks,
> >> Namhyung
> >>
> >>>
> >>> After:
> >>>   ...
> >>>   {"counter-value" : "<not counted>", "unit" : "", "event" : "cpu_atom/branch-misses/", "event-runtime" : 0, "pcnt-running" : 0.00}
> >>>   {"counter-value" : "5778.000000", "unit" : "", "event" : "cpu_core/branch-misses/", "event-runtime" : 282240, "pcnt-running" : 100.00, "metric-value" : "3.226797", "metric-unit" : "of all branches", "metric-threshold" : "good"}
> >>>   ...
> >>>
> >>> Signed-off-by: James Clark <james.clark@linaro.org>
> >>> ---
> >>>   tools/perf/util/stat-display.c | 2 +-
> >>>   1 file changed, 1 insertion(+), 1 deletion(-)
> >>>
> >>> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> >>> index a5d72f4a515c..9b7fd985a42a 100644
> >>> --- a/tools/perf/util/stat-display.c
> >>> +++ b/tools/perf/util/stat-display.c
> >>> @@ -506,7 +506,7 @@ static void print_metric_json(struct perf_stat_config *config __maybe_unused,
> >>>        struct outstate *os = ctx;
> >>>        FILE *out = os->fh;
> >>>
> >>> -     if (unit) {
> >>> +     if (unit && strlen(unit)) {
> >>>                json_out(os, "\"metric-value\" : \"%f\", \"metric-unit\" : \"%s\"", val, unit);
> >>>                if (thresh != METRIC_THRESHOLD_UNKNOWN) {
> >>>                        json_out(os, "\"metric-threshold\" : \"%s\"",
> >>> --
> >>> 2.34.1
> >>>
>