linux-kernel - Re: [PATCH 01/15] perf tools: Fix -n option

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Date:   Mon, 3 Jul 2017 11:57:39 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Namhyung Kim <namhyung@...nel.org>,
        David Ahern <dsahern@...il.com>,
        Thomas Richter <tmricht@...ux.vnet.ibm.com>
Subject: Re: [PATCH 01/15] perf tools: Fix -n option

Em Mon, Jul 03, 2017 at 04:50:16PM +0200, Jiri Olsa escreveu:
> The kernel fails to add a non sampling event event
> with having precise_ip set.
> 
> Make sure the precise_ip is 0 when using -n option
> to create non sampling event in record.

Ok, but how could that happen? What was the scenario? Which command? Can
you provide a command line that causes the problem?

I ask this because perhaps we should tell the user that what its being
asked on a command line doesn't make sense instead of dropping the
precise_ip as in your patch.

- Arnaldo
 
> Link: http://lkml.kernel.org/n/tip-l513fzc1houvu7tl1bo5y65y@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
> ---
>  tools/perf/util/evsel.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index 6f4882f8d61f..915fe3cd6544 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -890,8 +890,10 @@ void perf_evsel__config(struct perf_evsel *evsel, struct record_opts *opts,
>  		attr->sample_period = 0;
>  	}
>  
> -	if (opts->no_samples)
> +	if (opts->no_samples) {
>  		attr->sample_freq = 0;
> +		attr->precise_ip = 0;
> +	}
>  
>  	if (opts->inherit_stat)
>  		attr->inherit_stat = 1;
> -- 
> 2.9.4