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

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Message-ID: <62f485df-4f5e-64a2-1294-6e162de25556@arm.com>
Date:   Wed, 12 Oct 2022 12:13:36 +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,
        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: Re: [PATCH] perf: Fix "Track with sched_switch" test by not printing
 warnings in quiet mode



On 12/10/2022 12:10, James Clark wrote:
> Especially when CONFIG_LOCKDEP and other debug configs are enabled,
> Perf can print the following warning when running the "Track with
> sched_switch" test:

Oops got the wrong test name here and in the title. Should be "kernel
lock contention analysis 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);