linux-kernel - [tip:perf/core] perf tests: No need to set attr.sample

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Message-ID: <tip-lcob05qhawkuvsyuu9g1fld5@git.kernel.org>
Date:	Sat, 9 Jan 2016 08:33:01 -0800
From:	tip-bot for Arnaldo Carvalho de Melo <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	peterz@...radead.org, dsahern@...il.com, acme@...hat.com,
	linux-kernel@...r.kernel.org, mingo@...nel.org, jolsa@...hat.com,
	hpa@...or.com, namhyung@...nel.org, adrian.hunter@...el.com,
	wangnan0@...wei.com, tglx@...utronix.de
Subject: [tip:perf/core] perf tests:
  No need to set attr.sample_freq in the perf time to TSC test

Commit-ID:  4f4ba0e6afac4b181471f5f12bd87294bd8807f6
Gitweb:     http://git.kernel.org/tip/4f4ba0e6afac4b181471f5f12bd87294bd8807f6
Author:     Arnaldo Carvalho de Melo <acme@...hat.com>
AuthorDate: Thu, 7 Jan 2016 09:54:56 -0300
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Thu, 7 Jan 2016 11:26:54 -0300

perf tests: No need to set attr.sample_freq in the perf time to TSC test

We were asking for a 4kHz sample_freq, making the test fail needlessly
when the system reduced /proc/sys/kernel/perf_event_max_sample_rate
below that.

In this test we only look at the PERF_SAMPLE_TIME fields in PERF_RECORD_
meta events, no need to set sample_freq.

Thanks to Namhyung for suggesting that max_sample_rate could be the
reason for the test failure, seeing the 'perf test -vv' output I sent.

Before:

  # echo 1000 > /proc/sys/kernel/perf_event_max_sample_rate
  # perf test TSC
  45: Test converting perf time to TSC   : FAILED!

After:

  # perf test TSC
  45: Test converting perf time to TSC   : Ok
  # cat /proc/sys/kernel/perf_event_max_sample_rate
  1000

Cc: Adrian Hunter <adrian.hunter@...el.com>
Cc: David Ahern <dsahern@...il.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Namhyung Kim <namhyung@...nel.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Wang Nan <wangnan0@...wei.com>
Link: http://lkml.kernel.org/n/tip-lcob05qhawkuvsyuu9g1fld5@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/arch/x86/tests/perf-time-to-tsc.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/tools/perf/arch/x86/tests/perf-time-to-tsc.c b/tools/perf/arch/x86/tests/perf-time-to-tsc.c
index a289aa8..9d29ee2 100644
--- a/tools/perf/arch/x86/tests/perf-time-to-tsc.c
+++ b/tools/perf/arch/x86/tests/perf-time-to-tsc.c
@@ -41,7 +41,6 @@ int test__perf_time_to_tsc(int subtest __maybe_unused)
 		.mmap_pages	     = UINT_MAX,
 		.user_freq	     = UINT_MAX,
 		.user_interval	     = ULLONG_MAX,
-		.freq		     = 4000,
 		.target		     = {
 			.uses_mmap   = true,
 		},