linux-kernel - Re: [PATCH 10/16] perf tools: Add support for synthesized sample type

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Date:   Thu, 16 Apr 2020 11:54:26 -0300
From:   Arnaldo Carvalho de Melo <arnaldo.melo@...il.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Jiri Olsa <jolsa@...hat.com>, Andi Kleen <ak@...ux.intel.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/16] perf tools: Add support for synthesized sample type

Em Wed, Apr 01, 2020 at 01:16:07PM +0300, Adrian Hunter escreveu:
> For reporting purposes, an evsel sample can have a callchain synthesized
> from AUX area data. Add support for keeping track of synthesized sample
> types. Note, the recorded sample_type cannot be changed because it is
> needed to continue to parse events.
> 
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/perf/util/evsel.c |  2 +-
>  tools/perf/util/evsel.h | 15 ++++++++++++++-
>  2 files changed, 15 insertions(+), 2 deletions(-)
> 
> diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
> index eb880efbce16..60e6cd49dee3 100644
> --- a/tools/perf/util/evsel.c
> +++ b/tools/perf/util/evsel.c
> @@ -2136,7 +2136,7 @@ int perf_evsel__parse_sample(struct evsel *evsel, union perf_event *event,
>  		}
>  	}
>  
> -	if (evsel__has_callchain(evsel)) {
> +	if (type & PERF_SAMPLE_CALLCHAIN) {
>  		const u64 max_callchain_nr = UINT64_MAX / sizeof(u64);

This ends up looking unrelated, I had to go and look at the source to
see that this is just a simplification, i.e. earlier in this function
(perf_evsel__parse_sample) we have:

        u64 type = evsel->core.attr.sample_type;

So the above doesn't change anything, good, but slowed reviewing a bit,
please consider next time to have this in a separate patch, I'll do it
this time.

Thanks,

- Arnaldo
  
>  		OVERFLOW_CHECK_u64(array);
> diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
> index 53187c501ee8..e64ed4202cab 100644
> --- a/tools/perf/util/evsel.h
> +++ b/tools/perf/util/evsel.h
> @@ -104,6 +104,14 @@ struct evsel {
>  		perf_evsel__sb_cb_t	*cb;
>  		void			*data;
>  	} side_band;
> +	/*
> +	 * For reporting purposes, an evsel sample can have a callchain
> +	 * synthesized from AUX area data. Keep track of synthesized sample
> +	 * types here. Note, the recorded sample_type cannot be changed because
> +	 * it is needed to continue to parse events.
> +	 * See also evsel__has_callchain().
> +	 */
> +	__u64			synth_sample_type;
>  };
>  
>  struct perf_missing_features {
> @@ -398,7 +406,12 @@ static inline bool perf_evsel__has_branch_hw_idx(const struct evsel *evsel)
>  
>  static inline bool evsel__has_callchain(const struct evsel *evsel)
>  {
> -	return (evsel->core.attr.sample_type & PERF_SAMPLE_CALLCHAIN) != 0;
> +	/*
> +	 * For reporting purposes, an evsel sample can have a recorded callchain
> +	 * or a callchain synthesized from AUX area data.
> +	 */
> +	return evsel->core.attr.sample_type & PERF_SAMPLE_CALLCHAIN ||
> +	       evsel->synth_sample_type & PERF_SAMPLE_CALLCHAIN;
>  }
>  
>  struct perf_env *perf_evsel__env(struct evsel *evsel);
> -- 
> 2.17.1
> 

-- 

- Arnaldo