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

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Message-ID: <20230612023523.3918618-1-changbin.du@huawei.com>
Date:   Mon, 12 Jun 2023 10:35:23 +0800
From:   Changbin Du <changbin.du@...wei.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
CC:     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>, Changbin Du <changbin.du@...wei.com>
Subject: [PATCH] perf/doc: revise the description about PR_TASK_PERF_EVENTS_{ENABLE,DISABLE}

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