linux-kernel - [PATCH] perf evlist: Fix the warning logic about warn_user_request

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Message-Id: <20240318121150.1552888-1-spring.cxz@gmail.com>
Date: Mon, 18 Mar 2024 20:11:50 +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] perf evlist: Fix the warning logic about warn_user_request_cpu

The old logic in evlist__warn_user_requested_cpus incorrectly output
the warning message when I run 'perf record -C xxx' command on my
context(the cpu has 8 performance-cores and 8 efficient-cores.).

The old warning like this:
  # perf record -C 17
  WARNING: A requested CPU in '17' is not supported by PMU 'cpu_core' (CPUs 0-15) for event 'cycles:P'
  # perf record -C 14
  WARNING: A requested CPU in '14' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
  # perf record -C 14-17
  WARNING: A requested CPU in '15-16' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
  WARNING: A requested CPU in '15-16' is not supported by PMU 'cpu_core' (CPUs 0-15) for event 'cycles:P'

After patching, the warning is as follows
  # perf record -C 17
  WARNING: A requested CPU '17' in '17' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
  # perf record -C 14
  WARNING: A requested CPU '14' in '14' is not supported by PMU 'cpu_core' (CPUs 0-15) for event 'cycles:P'
  # perf record -C 15-18
  WARNING: A requested CPU '16-18' in '15-18' is not supported by PMU 'cpu_atom' (CPUs 16-23) for event 'cycles:P'
  WARNING: A requested CPU '15' in '15-18' is not supported by PMU 'cpu_core' (CPUs 0-15) for event 'cycles:P'

Signed-off-by: Chunxin Zang <spring.cxz@...il.com>
Reviewed-by: Chen Yang <yangchen11@...iang.com>
---
 tools/perf/util/evlist.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c
index 55a300a0977b..82fee2e29966 100644
--- a/tools/perf/util/evlist.c
+++ b/tools/perf/util/evlist.c
@@ -2514,12 +2514,16 @@ void evlist__warn_user_requested_cpus(struct evlist *evlist, const char *cpu_lis
 
 		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];
 
-			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));
+		if (intersect && perf_cpu_map__is_subset(user_requested_cpus, intersect)) {
+			char buf_test[128];
+			char buf_intersect[128];
+
+			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