linux-kernel - [PATCH v2] perf evlist: Fix 'perf record -C xx' failed issue

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Date: Tue, 19 Mar 2024 17:14:29 +0800
From: Chunxin Zang <spring.cxz@...il.com>
To: peterz@...radead.org,
	mingo@...hat.com,
	acme@...nel.org,
	namhyung@...nel.org,
	mark.rutland@....com,
	alexander.shishkin@...ux.intel.com,
	jolsa@...nel.org,
	irogers@...gle.com,
	adrian.hunter@...el.com
Cc: yangchen11@...iang.com,
	zhouchunhua@...iang.com,
	linux-perf-users@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	zangchunxin@...iang.com,
	Chunxin Zang <spring.cxz@...il.com>
Subject: [PATCH v2] perf evlist: Fix 'perf record -C xx' failed issue

The cpu has 8 performance-cores and 8 efficient-cores on my pc.
0-15 are performance-cores
16-23 are 8 efficient-cores

When I run "perf record -C xxx", the command fails if xxx all belong to
performance cores or efficient cores

The results are as follows

  # perf record -C 12
  WARNING: A requested CPU in '12' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
  Error:
  The sys_perf_event_open() syscall returned with 22 (Invalid argument) for event (cpu_atom/cycles:P/).
  /bin/dmesg | grep -i perf may provide additional information.

  # perf record -C 14-17
  WARNING: A requested CPU in '14-17' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
  WARNING: A requested CPU in '14-17' is not supported by PMU 'cpu_core' (CPUs 0-15) for event 'cycles:P'
  ^C[ perf record: Woken up 1 times to write data ]

The reason is that the cpu_map of 'cpu_atom'-evsel is empty, causing
the sys_perf_event_open() result to fail.

Changes in v2:
- fix memory leak about 'intersect'

Signed-off-by: Chunxin Zang <spring.cxz@...il.com>
Reviewed-by: Chen Yang <yangchen11@...iang.com>
---
 tools/perf/util/evlist.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 55a300a0977b..babbde29341f 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -2499,7 +2499,7 @@ void evlist__check_mem_load_aux(struct evlist *evlist)
 void evlist__warn_user_requested_cpus(struct evlist *evlist, const char *cpu_list)
 {
 	struct perf_cpu_map *user_requested_cpus;
-	struct evsel *pos;
+	struct evsel *pos, *tmp;
 
 	if (!cpu_list)
 		return;
@@ -2508,18 +2508,28 @@ void evlist__warn_user_requested_cpus(struct evlist *evlist, const char *cpu_lis
 	if (!user_requested_cpus)
 		return;
 
-	evlist__for_each_entry(evlist, pos) {
+	evlist__for_each_entry_safe(evlist, tmp, pos) {
 		struct perf_cpu_map *intersect, *to_test;
 		const struct perf_pmu *pmu = evsel__find_pmu(pos);
 
 		to_test = pmu && pmu->is_core ? pmu->cpus : cpu_map__online();
 		intersect = perf_cpu_map__intersect(to_test, user_requested_cpus);
-		if (!perf_cpu_map__equal(intersect, user_requested_cpus)) {
-			char buf[128];
+		if (!intersect) {
+			evlist__remove(evlist, pos);
+			evsel__delete(pos);
+			perf_cpu_map__put(intersect);
+			continue;
+		}
+
+		if (!perf_cpu_map__is_subset(user_requested_cpus, intersect)) {
+			char buf_test[128];
+			char buf_intersect[128];
 
-			cpu_map__snprint(to_test, buf, sizeof(buf));
-			pr_warning("WARNING: A requested CPU in '%s' is not supported by PMU '%s' (CPUs %s) for event '%s'\n",
-				cpu_list, pmu ? pmu->name : "cpu", buf, evsel__name(pos));
+			cpu_map__snprint(to_test, buf_test, sizeof(buf_test));
+			cpu_map__snprint(intersect, buf_intersect, sizeof(buf_intersect));
+			pr_warning("WARNING: A requested CPU '%s' in '%s' is not supported by "
+				   "PMU '%s' (CPUs %s) for event '%s'\n", buf_intersect, cpu_list,
+				   pmu ? pmu->name : "cpu", buf_test, evsel__name(pos));
 		}
 		perf_cpu_map__put(intersect);
 	}
-- 
2.34.1