linux-kernel - Re: [PATCH] perf/doc: revise the description about PR_TASK_PERF_EVENTS

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Date:   Tue, 18 Jul 2023 09:42:27 +0800
From:   Changbin Du <changbin.du@...wei.com>
To:     Changbin Du <changbin.du@...wei.com>
CC:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        <linux-perf-users@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <hw.huiwang@...wei.com>
Subject: Re: [PATCH] perf/doc: revise the description about
 PR_TASK_PERF_EVENTS_{ENABLE,DISABLE}

Hi Arnaldo,
Could you pick this? So I can update the prctl man pages as well.

On Mon, Jun 12, 2023 at 10:35:23AM +0800, Changbin Du wrote:
> The behavior of PR_TASK_PERF_EVENTS_{ENABLE,DISABLE} has been changed
> since v2.6.30, commit 082ff5a2767a ("perf_counter: Change pctrl()
> behaviour").
> 
> This patch revises the documentation about these two prctl options to match
> the real behavior. The linux man pages should also be updated.
> 
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Changbin Du <changbin.du@...wei.com>
> ---
>  tools/perf/design.txt | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
> 
> diff --git a/tools/perf/design.txt b/tools/perf/design.txt
> index aa8cfeabb743..cc9a2716d5ec 100644
> --- a/tools/perf/design.txt
> +++ b/tools/perf/design.txt
> @@ -439,16 +439,15 @@ Additionally, non-inherited overflow counters can use
>  
>  to enable a counter for 'nr' events, after which it gets disabled again.
>  
> -A process can enable or disable all the counter groups that are
> -attached to it, using prctl:
> +A thread can enable or disable all the counter groups that are
> +created by itself, using prctl:
>  
>  	prctl(PR_TASK_PERF_EVENTS_ENABLE);
>  
>  	prctl(PR_TASK_PERF_EVENTS_DISABLE);
>  
> -This applies to all counters on the current process, whether created
> -by this process or by another, and doesn't affect any counters that
> -this process has created on other processes.  It only enables or
> +This applies to all counters created by this thread, and doesn't affect any
> +counters that created by other processes or threads.  It only enables or
>  disables the group leaders, not any other members in the groups.
>  
>  
> -- 
> 2.25.1
> 

-- 
Cheers,
Changbin Du