linux-kernel - [PATCH 3/4] perf hist: Do not use event index in hpp_

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Date: Mon, 12 Feb 2024 23:52:55 -0800
From: Namhyung Kim <namhyung@...nel.org>
To: Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ian Rogers <irogers@...gle.com>
Cc: Jiri Olsa <jolsa@...nel.org>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-perf-users@...r.kernel.org
Subject: [PATCH 3/4] perf hist: Do not use event index in hpp__fmt()

The __hpp__fmt() is to print period values in a hist entry.  It handles
event groups using linked pair entries.  Until now, it used event index
to print values of group members.  But we want to make it more robust
and support groups even if some members in the group were removed.

Let's use an index table from evsel to value array so that we can skip
dummy events in the output later.

Signed-off-by: Namhyung Kim <namhyung@...nel.org>
---
 tools/perf/ui/hist.c | 34 ++++++++++++++++++++++++++++------
 1 file changed, 28 insertions(+), 6 deletions(-)

diff --git a/tools/perf/ui/hist.c b/tools/perf/ui/hist.c
index 5f4c110d840f..9c4c738edde1 100644
--- a/tools/perf/ui/hist.c
+++ b/tools/perf/ui/hist.c
@@ -48,15 +48,30 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hist_entry *he,
 	if (evsel__is_group_event(evsel)) {
 		int idx;
 		struct hist_entry *pair;
-		int nr_members = evsel->core.nr_members;
+		int nr_members = evsel->core.nr_members - 1;
 		union {
 			u64 period;
 			double percent;
 		} *val;
+		struct evsel *member;
+		struct evsel **idx_table;
 
 		val = calloc(nr_members, sizeof(*val));
 		if (val == NULL)
-			return 0;
+			goto out;
+
+		idx_table = calloc(nr_members, sizeof(*idx_table));
+		if (idx_table == NULL)
+			goto out;
+
+		/*
+		 * Build an index table for each evsel to the val array.
+		 * It cannot use evsel->core.idx because removed events might
+		 * create a hole so the index is not consecutive anymore.
+		 */
+		idx = 0;
+		for_each_group_member(member, evsel)
+			idx_table[idx++] = member;
 
 		/* collect values in the group members */
 		list_for_each_entry(pair, &he->pairs.head, pairs.node) {
@@ -66,8 +81,15 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hist_entry *he,
 			if (!total)
 				continue;
 
-			evsel = hists_to_evsel(pair->hists);
-			idx = evsel__group_idx(evsel);
+			member = hists_to_evsel(pair->hists);
+			for (idx = 0; idx < nr_members; idx++) {
+				if (idx_table[idx] == member)
+					break;
+			}
+
+			/* this should not happen */
+			if (idx == nr_members)
+				continue;
 
 			if (fmt_percent)
 				val[idx].percent = 100.0 * period / total;
@@ -75,8 +97,7 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hist_entry *he,
 				val[idx].period = period;
 		}
 
-		/* idx starts from 1 to skip the leader event */
-		for (idx = 1; idx < nr_members; idx++) {
+		for (idx = 0; idx < nr_members; idx++) {
 			if (fmt_percent) {
 				ret += hpp__call_print_fn(hpp, print_fn,
 							  fmt, len, val[idx].percent);
@@ -89,6 +110,7 @@ static int __hpp__fmt(struct perf_hpp *hpp, struct hist_entry *he,
 		free(val);
 	}
 
+out:
 	/*
 	 * Restore original buf and size as it's where caller expects
 	 * the result will be saved.
-- 
2.43.0.687.g38aa6559b0-goog