[RFC PATCH v4 09/15] perf stat: Add function to handle special events in hardware-grouping

[weilin . wang]

From: Weilin Wang <weilin.wang@xxxxxxxxx>

There are some special events like topdown events and TSC that are not
described in pmu-event JSON files. Add support to handle this type of
events. This should be considered as a temporary solution because including
these events in JSON files would be a better solution.

Signed-off-by: Weilin Wang <weilin.wang@xxxxxxxxx>
---
 tools/perf/util/metricgroup.c | 38 ++++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index 660c6b9b5fa7..a0579b0f81e5 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -160,6 +160,20 @@ struct metric {
 
 /* Maximum number of counters per PMU*/
 #define NR_COUNTERS	16
+/* Special events that are not described in pmu-event JSON files.
+ * topdown-* and TSC use dedicated registers, set as free
+ * counter for grouping purpose
+ */
+enum special_events {
+	TOPDOWN	= 0,
+	TSC	= 1,
+	SPECIAL_EVENT_MAX,
+};
+
+static const char *const special_event_names[SPECIAL_EVENT_MAX] = {
+	"topdown-",
+	"TSC",
+};
 
 /**
  * An event used in a metric. This info is for metric grouping.
@@ -2102,6 +2116,15 @@ static int create_grouping(struct list_head *pmu_info_list,
 	return ret;
 };
 
+static bool is_special_event(const char *id)
+{
+	for (int i = 0; i < SPECIAL_EVENT_MAX; i++) {
+		if (!strncmp(id, special_event_names[i], strlen(special_event_names[i])))
+			return true;
+	}
+	return false;
+}
+
 /**
  * hw_aware_build_grouping - Build event groupings by reading counter
  * requirement of the events and counter available on the system from
@@ -2126,6 +2149,17 @@ static int hw_aware_build_grouping(struct expr_parse_ctx *ctx __maybe_unused,
 	hashmap__for_each_entry(ctx->ids, cur, bkt) {
 		const char *id = cur->pkey;
 
+		if (is_special_event(id)) {
+			struct metricgroup__event_info *event;
+
+			event = event_info__new(id, "default_core", "0",
+						/*free_counter=*/true);
+			if (!event)
+				goto err_out;
+
+			list_add(&event->nd, &event_info_list);
+			continue;
+		}
 		ret = get_metricgroup_events(id, etable, &event_info_list);
 		if (ret)
 			goto err_out;
@@ -2597,8 +2631,10 @@ int metricgroup__parse_groups(struct evlist *perf_evlist,
 		ret = hw_aware_parse_groups(perf_evlist, pmu, str,
 			    metric_no_threshold, user_requested_cpu_list, system_wide,
 			    /*fake_pmu=*/NULL, metric_events, table);
-		if (!ret)
+		if (!ret) {
+			pr_info("Hardware aware grouping completed\n");
 			return 0;
+		}
 	}
 
 	return parse_groups(perf_evlist, pmu, str, metric_no_group, metric_no_merge,
-- 
2.42.0