linux-kernel - Re: [PATCH 28/52] perf script: Allow callchains if any event samples them

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Date:	Fri, 25 Jul 2014 10:27:05 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Adrian Hunter <adrian.hunter@...el.com>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	linux-kernel@...r.kernel.org, David Ahern <dsahern@...il.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Jiri Olsa <jolsa@...hat.com>,
	Namhyung Kim <namhyung@...il.com>,
	Paul Mackerras <paulus@...ba.org>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 28/52] perf script: Allow callchains if any event samples
 them

Em Tue, Jul 22, 2014 at 04:17:37PM +0300, Adrian Hunter escreveu:
> perf script was not displaying callchains if any selected
> event did not have PERF_SAMPLE_CALLCHAIN.  Change this to
> disable callchains only if all selected events do not have
> PERF_SAMPLE_CALLCHAIN.

I wonder if some other tool gets this wrong as well, report maybe?

Perhaps we need to have this check in some perf_evlist method?

Wonder how report/top, i.e. the hists browser will react with some
events having callchains while some don't, specially with this new
children stuff, Namhyung, can you please check that?

Adrian, can you, in a case like that, provide a command line that
creates such combo? I.e. how to create a perf.data file with multiple
events with some having callchains while some don't.

As a rule, it is better to ease reproducing behaviour you mention when
fixing stuff, so that quickly others can try and go on trying to fix it.

Thanks,

- Arnaldo
 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/perf/builtin-script.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
> index 582da97..c1a56f2 100644
> --- a/tools/perf/builtin-script.c
> +++ b/tools/perf/builtin-script.c
> @@ -184,10 +184,6 @@ static int perf_evsel__check_attr(struct perf_evsel *evsel,
>  		if (perf_evsel__check_stype(evsel, PERF_SAMPLE_IP, "IP",
>  					    PERF_OUTPUT_IP))
>  			return -EINVAL;
> -
> -		if (!no_callchain &&
> -		    !(attr->sample_type & PERF_SAMPLE_CALLCHAIN))
> -			symbol_conf.use_callchain = false;
>  	}
>  
>  	if (PRINT_FIELD(ADDR) &&
> @@ -290,6 +286,19 @@ static int perf_session__check_output_opt(struct perf_session *session)
>  		set_print_ip_opts(&evsel->attr);
>  	}
>  
> +	if (!no_callchain) {
> +		bool use_callchain = false;
> +
> +		evlist__for_each(session->evlist, evsel) {
> +			if (evsel->attr.sample_type & PERF_SAMPLE_CALLCHAIN) {
> +				use_callchain = true;
> +				break;
> +			}
> +		}
> +		if (!use_callchain)
> +			symbol_conf.use_callchain = false;
> +	}
> +
>  	/*
>  	 * set default for tracepoints to print symbols only
>  	 * if callchains are present
> -- 
> 1.8.3.2
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