linux-kernel - [PATCH 1/2] perf_event_open.2: Document PERF_EVENT_IOC_PAUSE

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Message-ID: <1477049893-143199-1-git-send-email-wangnan0@huawei.com>
Date:   Fri, 21 Oct 2016 11:38:12 +0000
From:   Wang Nan <wangnan0@...wei.com>
To:     <mtk.manpages@...il.com>
CC:     <wangnan0@...wei.com>, <pi3orama@....com>,
        <linux-kernel@...r.kernel.org>, <linux-man@...r.kernel.org>,
        <lizefan@...wei.com>, <vincent.weaver@...ne.edu>
Subject: [PATCH 1/2] perf_event_open.2: Document PERF_EVENT_IOC_PAUSE_OUTPUT

Linux 4.7 (86e7972f690c1017fd086cdfe53d8524e68c661c) introduces
PERF_EVENT_IOC_PAUSE_OUTPUT feature. Document it.

Signed-off-by: Wang Nan <wangnan0@...wei.com>
Cc: Michael Kerrisk <mtk.manpages@...il.com>
---
 man2/perf_event_open.2 | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2
index fade28c..2d3acad 100644
--- a/man2/perf_event_open.2
+++ b/man2/perf_event_open.2
@@ -2865,7 +2865,18 @@ The argument is a BPF program file descriptor that was created by
 a previous
 .BR bpf (2)
 system call.
-.SS Using prctl(2)
+.TP
+.BR PERF_EVENT_IOC_PAUSE_OUTPUT " (since Linux 4.7)"
+.\" commit 86e7972f690c1017fd086cdfe53d8524e68c661c
+This allows pausing and resuming the event's ring-buffer. A
+paused ring-buffer does not prevent samples generation, but simply
+discards them. The discarded samples are considered lost, causes
+.BR PERF_RECORD_LOST
+to be generated when possible.
+
+The argument is an integer. Nonzero value pauses the ring-buffer,
+zero value resumes the ring-buffer.
+.SS Using prctl
 A process can enable or disable all the event groups that are
 attached to it using the
 .BR prctl (2)
-- 
2.10.1