linux-kernel - [PATCH 04/22] perf tests: Use perf_evlist__strerror_open() to provide hints about max

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Date:	Fri, 19 Feb 2016 19:41:18 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Steven Noonan <steven@...inklabs.net>,
	Wang Nan <wangnan0@...wei.com>
Subject: [PATCH 04/22] perf tests: Use perf_evlist__strerror_open() to provide hints about max_freq

From: Arnaldo Carvalho de Melo <acme@...hat.com>

Before:

  # perf test -v "code reading" 2>&1 | tail -4
  perf_evlist__open failed
  test child finished with -1
  ---- end ----
  Test object code reading: FAILED!
  #

After:

  # perf test -v "code reading" 2>&1 | tail -7
  perf_evlist__open() failed!
  Error: Invalid argument.
  Hint:  Check /proc/sys/kernel/perf_event_max_sample_rate.
  Hint:  The current value is 1000 and 4000 is being requested.
  test child finished with -1
  ---- end ----
  Test object code reading: FAILED!
  #

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: Jiri Olsa <jolsa@...nel.org>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Steven Noonan <steven@...inklabs.net>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-ifbx7vmrc38loe6317owz2jx@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/tests/code-reading.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/tools/perf/tests/code-reading.c b/tools/perf/tests/code-reading.c
index 313a48c6b2bc..f84339cb7f95 100644
--- a/tools/perf/tests/code-reading.c
+++ b/tools/perf/tests/code-reading.c
@@ -559,7 +559,13 @@ static int do_test_code_reading(bool try_kcore)
 				evlist = NULL;
 				continue;
 			}
-			pr_debug("perf_evlist__open failed\n");
+
+			if (verbose) {
+				char errbuf[512];
+				perf_evlist__strerror_open(evlist, errno, errbuf, sizeof(errbuf));
+				pr_debug("perf_evlist__open() failed!\n%s\n", errbuf);
+			}
+
 			goto out_put;
 		}
 		break;
-- 
2.5.0