linux-kernel - [PATCH] perf: Fix "Track with sched_switch" test by not printing warnings in quiet mode

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Message-Id: <20221012111025.30609-1-james.clark@arm.com>
Date:   Wed, 12 Oct 2022 12:10:24 +0100
From:   James Clark <james.clark@....com>
To:     linux-perf-users@...r.kernel.org, acme@...nel.org,
        namhyung@...nel.org
Cc:     linux-kernel@...r.kernel.org, James Clark <james.clark@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>
Subject: [PATCH] perf: Fix "Track with sched_switch" test by not printing warnings in quiet mode

Especially when CONFIG_LOCKDEP and other debug configs are enabled,
Perf can print the following warning when running the "Track with
sched_switch" test:

  Warning:
  Processed 1378918 events and lost 4 chunks!

  Check IO/CPU overload!

  Warning:
  Processed 4593325 samples and lost 70.00%!

The test already supplies -q to run in quiet mode, so extend quiet mode
to perf_stdio__warning() and also ui__warning() for consistency.

This fixes the following failure due to the extra lines counted:

  perf test "lock cont" -vvv

  82: kernel lock contention analysis test                            :
  --- start ---
  test child forked, pid 3125
  Testing perf lock record and perf lock contention
  [Fail] Recorded result count is not 1: 9
  test child finished with -1
  ---- end ----
  kernel lock contention analysis test: FAILED!

Fixes: ec685de25b67 ("perf test: Add kernel lock contention test")
Cc: Namhyung Kim <namhyung@...nel.org>
Signed-off-by: James Clark <james.clark@....com>
---
 tools/perf/ui/util.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/tools/perf/ui/util.c b/tools/perf/ui/util.c
index 689b27c34246..1d38ddf01b60 100644
--- a/tools/perf/ui/util.c
+++ b/tools/perf/ui/util.c
@@ -15,6 +15,9 @@ static int perf_stdio__error(const char *format, va_list args)
 
 static int perf_stdio__warning(const char *format, va_list args)
 {
+	if (quiet)
+		return 0;
+
 	fprintf(stderr, "Warning:\n");
 	vfprintf(stderr, format, args);
 	return 0;
@@ -45,6 +48,8 @@ int ui__warning(const char *format, ...)
 {
 	int ret;
 	va_list args;
+	if (quiet)
+		return 0;
 
 	va_start(args, format);
 	ret = perf_eops->warning(format, args);
-- 
2.28.0