[PATCH v2 0/2] perf stat: Fix trailing comma when there is no metric unit

[PATCH v2 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-units exclusion from the JSON should be consistent if we're going
to have it at all.

Changes since v1:

  * Don't skip printing when the metric-unit string is empty but pass
    NULL instead of an empty string.

James Clark (2):
  perf stat: Fix trailing comma when there is no metric unit
  perf stat: Also hide metric-units from JSON when event didn't run

 .../tests/shell/lib/perf_json_output_lint.py  |  14 +-
 tools/perf/util/stat-display.c                | 182 ++++++++++--------
 2 files changed, 107 insertions(+), 89 deletions(-)

-- 
2.34.1

[PATCH v2 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

Re: [PATCH v2 1/2] perf stat: Fix trailing comma when there is no metric unit

[Ian Rogers]

On Wed, Oct 30, 2024 at 4:40 AM James Clark <james.clark@linaro.org> wrote:
>
> 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.

Thanks for the larger clean up!

> 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;

It'd be nice to have kernel-doc capturing the meaning of these
variables. newline and first, why would something be a newline but not
first? I know the lack of documentation is a pre-existing condition.
Pretty much every variable in the struct below confuses me and I need
to read the code to try to figure it out.

> +       const char *prefix;

Prefix of what?

> +       int  nfields;

Is this the number of columns in CSV format? Why not a name like
csv_columns then? What is a field here?

> +       int  aggr_nr;
> +       struct aggr_cpu_id id;

Something to do with aggregation, presumably for the current CSV line.
Why two of them?

> +       struct evsel *evsel;
> +       struct cgroup *cgrp;

Maybe the counter and cgroup being printed, but we usually pass those
as extra arguments. This loses me.

I was hoping the code here could be more like the perf list json:
https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/builtin-list.c?h=perf-tools-next#n357
which avoids the comma problem by printing everything in one go.
There's so much spaghetti code in stat-display and before we had tests
there were frequent breakages. Anyway, I don't expect a larger clean
up, just venting. If you could do the comments and clear up the
newline vs first it'd be great.

Thanks,
Ian

> +};
>
> -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
>

Re: [PATCH v2 1/2] perf stat: Fix trailing comma when there is no metric unit

[James Clark]

On 31/10/2024 4:17 am, Ian Rogers wrote:
> On Wed, Oct 30, 2024 at 4:40 AM James Clark <james.clark@linaro.org> wrote:
>>
>> 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.
> 
> Thanks for the larger clean up!
> 
>> 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;
> 
> It'd be nice to have kernel-doc capturing the meaning of these
> variables. newline and first, why would something be a newline but not
> first? I know the lack of documentation is a pre-existing condition.
> Pretty much every variable in the struct below confuses me and I need
> to read the code to try to figure it out.
> 
>> +       const char *prefix;
> 
> Prefix of what?
> 
>> +       int  nfields;
> 
> Is this the number of columns in CSV format? Why not a name like
> csv_columns then? What is a field here?
> 
>> +       int  aggr_nr;
>> +       struct aggr_cpu_id id;
> 
> Something to do with aggregation, presumably for the current CSV line.
> Why two of them?
> 
>> +       struct evsel *evsel;
>> +       struct cgroup *cgrp;
> 
> Maybe the counter and cgroup being printed, but we usually pass those
> as extra arguments. This loses me.
> 
> I was hoping the code here could be more like the perf list json:
> https://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools-next.git/tree/tools/perf/builtin-list.c?h=perf-tools-next#n357
> which avoids the comma problem by printing everything in one go.
> There's so much spaghetti code in stat-display and before we had tests
> there were frequent breakages. Anyway, I don't expect a larger clean
> up, just venting. If you could do the comments and clear up the
> newline vs first it'd be great.
> 
> Thanks,
> Ian
> 

Yep I can do that.

Thanks for the review.

[PATCH v2 2/2] perf stat: Also hide metric-units from JSON when event didn't run

[James Clark]

We decided to hide NULL metric-units rather than showing it as "(null)"
when a dependent event for a metric doesn't exist. But on hybrid systems
if the process doesn't hit a PMU you get an empty string metric unit
instead. To make it consistent change all empty strings to NULL.

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 | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index a5d72f4a515c..0e16eecfbad8 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -854,7 +854,8 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
 
 	if (run == 0 || ena == 0 || counter->counts->scaled == -1) {
 		if (config->metric_only) {
-			pm(config, os, METRIC_THRESHOLD_UNKNOWN, "", "", 0);
+			pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL,
+			   /*unit=*/NULL, /*val=*/0);
 			return;
 		}
 
@@ -909,7 +910,7 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
 			perf_stat__print_shadow_stats(config, counter, uval, aggr_idx,
 						      &out, &config->metric_events);
 	} else {
-		pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/"", /*val=*/0);
+		pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/NULL, /*val=*/0);
 	}
 
 	if (!config->metric_only) {
-- 
2.34.1

Re: [PATCH v2 2/2] perf stat: Also hide metric-units from JSON when event didn't run

[Ian Rogers]

On Wed, Oct 30, 2024 at 4:40 AM James Clark <james.clark@linaro.org> wrote:
>
> We decided to hide NULL metric-units rather than showing it as "(null)"
> when a dependent event for a metric doesn't exist. But on hybrid systems
> if the process doesn't hit a PMU you get an empty string metric unit
> instead. To make it consistent change all empty strings to NULL.
>
> 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>

Reviewed-by: Ian Rogers <irogers@google.com>

Thanks,
Ian

> ---
>  tools/perf/util/stat-display.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
> index a5d72f4a515c..0e16eecfbad8 100644
> --- a/tools/perf/util/stat-display.c
> +++ b/tools/perf/util/stat-display.c
> @@ -854,7 +854,8 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
>
>         if (run == 0 || ena == 0 || counter->counts->scaled == -1) {
>                 if (config->metric_only) {
> -                       pm(config, os, METRIC_THRESHOLD_UNKNOWN, "", "", 0);
> +                       pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL,
> +                          /*unit=*/NULL, /*val=*/0);
>                         return;
>                 }
>
> @@ -909,7 +910,7 @@ static void printout(struct perf_stat_config *config, struct outstate *os,
>                         perf_stat__print_shadow_stats(config, counter, uval, aggr_idx,
>                                                       &out, &config->metric_events);
>         } else {
> -               pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/"", /*val=*/0);
> +               pm(config, os, METRIC_THRESHOLD_UNKNOWN, /*format=*/NULL, /*unit=*/NULL, /*val=*/0);
>         }
>
>         if (!config->metric_only) {
> --
> 2.34.1
>