linux-kernel - Re: [PATCH v7] perf annotate: Fix sample events lost in stdio mode

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Date:   Fri, 26 Mar 2021 10:24:30 +0800
From:   Yang Jihong <yangjihong1@...wei.com>
To:     <peterz@...radead.org>, <mingo@...hat.com>, <acme@...nel.org>,
        <mark.rutland@....com>, <alexander.shishkin@...ux.intel.com>,
        <jolsa@...hat.com>, <namhyung@...nel.org>,
        <yao.jin@...ux.intel.com>, <gustavoars@...nel.org>,
        <mliska@...e.cz>, <linux-kernel@...r.kernel.org>
CC:     <zhangjinhao2@...wei.com>
Subject: Re: [PATCH v7] perf annotate: Fix sample events lost in stdio mode

Hello,
ping :)

On 2021/3/19 20:35, Yang Jihong wrote:
> In hist__find_annotations function, since different hist_entry may point to same
> symbol, we free notes->src to signal already processed this symbol in stdio mode;
> when annotate, entry will skipped if notes->src is NULL to avoid repeated output.
> 
> However, there is a problem, for example, run the following command:
> 
>   # perf record -e branch-misses -e branch-instructions -a sleep 1
> 
> perf.data file contains different types of sample event.
> 
> If the same IP sample event exists in branch-misses and branch-instructions,
> this event uses the same symbol. When annotate branch-misses events, notes->src
> corresponding to this event is set to null, as a result, when annotate
> branch-instructions events, this event is skipped and no annotate is output.
> 
> Solution of this patch is to remove zfree in hists__find_annotations and
> change sort order to "dso,symbol" to avoid duplicate output when different
> processes correspond to the same symbol.
> 
> Signed-off-by: Yang Jihong <yangjihong1@...wei.com>
> ---
> 
> Changes since v6:
>    - Remove separate setup_sorting() for branch mode.
> 
> Changes since v5:
>    - Add Signed-off-by tag.
> 
> Changes since v4:
>    - Use the same sort key "dso,symbol" in branch stack mode.
> 
> Changes since v3:
>    - Modify the first line of comments.
> 
> Changes since v2:
>    - Remove zfree in hists__find_annotations.
>    - Change sort order to avoid duplicate output.
> 
> Changes since v1:
>    - Change processed flag variable from u8 to bool.
> 
>   tools/perf/builtin-annotate.c | 29 +++++++++++++++--------------
>   1 file changed, 15 insertions(+), 14 deletions(-)
> 
> diff --git a/tools/perf/builtin-annotate.c b/tools/perf/builtin-annotate.c
> index a23ba6bb99b6..795c2ac7fcd1 100644
> --- a/tools/perf/builtin-annotate.c
> +++ b/tools/perf/builtin-annotate.c
> @@ -374,13 +374,6 @@ static void hists__find_annotations(struct hists *hists,
>   		} else {
>   			hist_entry__tty_annotate(he, evsel, ann);
>   			nd = rb_next(nd);
> -			/*
> -			 * Since we have a hist_entry per IP for the same
> -			 * symbol, free he->ms.sym->src to signal we already
> -			 * processed this symbol.
> -			 */
> -			zfree(&notes->src->cycles_hist);
> -			zfree(&notes->src);
>   		}
>   	}
>   }
> @@ -619,14 +612,22 @@ int cmd_annotate(int argc, const char **argv)
>   
>   	setup_browser(true);
>   
> -	if ((use_browser == 1 || annotate.use_stdio2) && annotate.has_br_stack) {
> +	/*
> +	 * Events of different processes may correspond to the same
> +	 * symbol, we do not care about the processes in annotate,
> +	 * set sort order to avoid repeated output.
> +	 */
> +	sort_order = "dso,symbol";
> +
> +	/*
> +	 * Set SORT_MODE__BRANCH so that annotate display IPC/Cycle
> +	 * if branch info is in perf data in TUI mode.
> +	 */
> +	if ((use_browser == 1 || annotate.use_stdio2) && annotate.has_br_stack)
>   		sort__mode = SORT_MODE__BRANCH;
> -		if (setup_sorting(annotate.session->evlist) < 0)
> -			usage_with_options(annotate_usage, options);
> -	} else {
> -		if (setup_sorting(NULL) < 0)
> -			usage_with_options(annotate_usage, options);
> -	}
> +
> +	if (setup_sorting(NULL) < 0)
> +		usage_with_options(annotate_usage, options);
>   
>   	ret = __cmd_annotate(&annotate);
>   
>