perf parse-events: Warn when events are regrouped

Use if an event is reordered or the number of groups increases to
signal that regrouping has happened and warn about it. Disable the
warning in the case wild card PMU names are used and for metrics.

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Florian Fischer <florian.fischer@muhq.space>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Garry <john.g.garry@oracle.com>
Cc: Kajol Jain <kjain@linux.ibm.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Kim Phillips <kim.phillips@amd.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@amd.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Steinar H. Gunderson <sesse@google.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Suzuki Poulouse <suzuki.poulose@arm.com>
Cc: Xing Zhengjun <zhengjun.xing@linux.intel.com>
Link: https://lore.kernel.org/r/20230312021543.3060328-2-irogers@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/parse-events.c

@@ -2103,7 +2103,7 @@ static int test_event_fake_pmu(const char *str)
 
 	parse_events_error__init(&err);
 	perf_pmu__test_parse_init();
-	ret = __parse_events(evlist, str, &err, &perf_pmu__fake);
+	ret = __parse_events(evlist, str, &err, &perf_pmu__fake, /*warn_if_reordered=*/true);
 	if (ret) {
 		pr_debug("failed to parse event '%s', err %d, str '%s'\n",
 			 str, ret, err.str);

tools/perf/tests/pmu-events.c

@@ -785,7 +785,7 @@ static int check_parse_id(const char *id, struct parse_events_error *error,
 		 */
 		perf_pmu__test_parse_init();
 	}
-	ret = __parse_events(evlist, dup, error, fake_pmu);
+	ret = __parse_events(evlist, dup, error, fake_pmu, /*warn_if_reordered=*/true);
 	free(dup);
 
 	evlist__delete(evlist);

tools/perf/util/metricgroup.c

@@ -1441,7 +1441,8 @@ static int parse_ids(bool metric_no_merge, struct perf_pmu *fake_pmu,
 	}
 	pr_debug("Parsing metric events '%s'\n", events.buf);
 	parse_events_error__init(&parse_error);
-	ret = __parse_events(parsed_evlist, events.buf, &parse_error, fake_pmu);
+	ret = __parse_events(parsed_evlist, events.buf, &parse_error, fake_pmu,
+			     /*warn_if_reordered=*/false);
 	if (ret) {
 		parse_events_error__print(&parse_error, events.buf);
 		goto err_out;

tools/perf/util/parse-events.c

@@ -2157,11 +2157,13 @@ static int evlist__cmp(void *state, const struct list_head *l, const struct list
 	return arch_evlist__cmp(lhs, rhs);
 }
 
-static void parse_events__sort_events_and_fix_groups(struct list_head *list)
+static bool parse_events__sort_events_and_fix_groups(struct list_head *list)
 {
-	int idx = -1;
+	int idx = 0, unsorted_idx = -1;
 	struct evsel *pos, *cur_leader = NULL;
 	struct perf_evsel *cur_leaders_grp = NULL;
+	bool idx_changed = false;
+	int orig_num_leaders = 0, num_leaders = 0;
 
 	/*
 	 * Compute index to insert ungrouped events at. Place them where the
@@ -2170,15 +2172,22 @@ static void parse_events__sort_events_and_fix_groups(struct list_head *list)
 	list_for_each_entry(pos, list, core.node) {
 		const struct evsel *pos_leader = evsel__leader(pos);
 
-		if (pos != pos_leader || pos->core.nr_members > 1)
+		if (pos == pos_leader)
-			continue;
+			orig_num_leaders++;
 
-		idx = pos->core.idx;
+		/*
-		break;
+		 * Ensure indexes are sequential, in particular for multiple
+		 * event lists being merged. The indexes are used to detect when
+		 * the user order is modified.
+		 */
+		pos->core.idx = idx++;
+
+		if (unsorted_idx == -1 && pos == pos_leader && pos->core.nr_members < 2)
+			unsorted_idx = pos->core.idx;
 	}
 
 	/* Sort events. */
-	list_sort(&idx, list, evlist__cmp);
+	list_sort(&unsorted_idx, list, evlist__cmp);
 
 	/*
 	 * Recompute groups, splitting for PMUs and adding groups for events
@@ -2192,6 +2201,8 @@ static void parse_events__sort_events_and_fix_groups(struct list_head *list)
 		bool force_grouped = arch_evsel__must_be_in_group(pos);
 
 		/* Reset index and nr_members. */
+		if (pos->core.idx != idx)
+			idx_changed = true;
 		pos->core.idx = idx++;
 		pos->core.nr_members = 0;
 
@@ -2225,12 +2236,18 @@ static void parse_events__sort_events_and_fix_groups(struct list_head *list)
 		}
 	}
 	list_for_each_entry(pos, list, core.node) {
-		pos->core.leader->nr_members++;
+		struct evsel *pos_leader = evsel__leader(pos);
+
+		if (pos == pos_leader)
+			num_leaders++;
+		pos_leader->core.nr_members++;
 	}
+	return idx_changed || num_leaders != orig_num_leaders;
 }
 
 int __parse_events(struct evlist *evlist, const char *str,
-		   struct parse_events_error *err, struct perf_pmu *fake_pmu)
+		   struct parse_events_error *err, struct perf_pmu *fake_pmu,
+		   bool warn_if_reordered)
 {
 	struct parse_events_state parse_state = {
 		.list	  = LIST_HEAD_INIT(parse_state.list),
@@ -2250,7 +2267,9 @@ int __parse_events(struct evlist *evlist, const char *str,
 		return -1;
 	}
 
-	parse_events__sort_events_and_fix_groups(&parse_state.list);
+	if (parse_events__sort_events_and_fix_groups(&parse_state.list) &&
+	    warn_if_reordered && !parse_state.wild_card_pmus)
+		pr_warning("WARNING: events were regrouped to match PMUs\n");
 
 	/*
 	 * Add list to the evlist even with errors to allow callers to clean up.

tools/perf/util/parse-events.h

@@ -26,13 +26,13 @@ int parse_events_option(const struct option *opt, const char *str, int unset);
 int parse_events_option_new_evlist(const struct option *opt, const char *str, int unset);
 __attribute__((nonnull(1, 2, 3)))
 int __parse_events(struct evlist *evlist, const char *str, struct parse_events_error *error,
-		   struct perf_pmu *fake_pmu);
+		   struct perf_pmu *fake_pmu, bool warn_if_reordered);
 
-__attribute__((nonnull))
+__attribute__((nonnull(1, 2, 3)))
 static inline int parse_events(struct evlist *evlist, const char *str,
 			       struct parse_events_error *err)
 {
-	return __parse_events(evlist, str, err, NULL);
+	return __parse_events(evlist, str, err, /*fake_pmu=*/NULL, /*warn_if_reordered=*/true);
 }
 
 int parse_event(struct evlist *evlist, const char *str);
@@ -128,6 +128,7 @@ struct parse_events_state {
 	int			   stoken;
 	struct perf_pmu		  *fake_pmu;
 	char			  *hybrid_pmu_name;
+	bool			   wild_card_pmus;
 };
 
 void parse_events__shrink_config_terms(void);

tools/perf/util/parse-events.y

@@ -323,6 +323,7 @@ event_pmu_name opt_pmu_config
 				if (!parse_events_add_pmu(_parse_state, list, pmu->name, terms,
 							  /*auto_merge_stats=*/true)) {
 					ok++;
+					parse_state->wild_card_pmus = true;
 				}
 				parse_events_terms__delete(terms);
 			}