linux-kernel - Re: [PATCH 1/5] perf core: Introduce new ioctl options to pause and resume ring buffer

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Message-ID: <aed4b8b0-2667-6482-40bb-d02aa3dc8873@gmail.com>
Date:   Fri, 21 Oct 2016 09:06:05 +0200
From:   "Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
To:     "Wangnan (F)" <wangnan0@...wei.com>,
        Peter Zijlstra <peterz@...radead.org>
Cc:     mtk.manpages@...il.com, mingo@...hat.com,
        linux-kernel@...r.kernel.org, He Kuang <hekuang@...wei.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Arnaldo Carvalho de Melo <acme@...hat.com>,
        Brendan Gregg <brendan.d.gregg@...il.com>,
        Jiri Olsa <jolsa@...nel.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Zefan Li <lizefan@...wei.com>, pi3orama@....com,
        Vince Weaver <vince@...ter.net>
Subject: Re: [PATCH 1/5] perf core: Introduce new ioctl options to pause and
 resume ring buffer

Hello Wangnan,

The patch below seems to have landed in Linux 4.7,
commit 86e7972f690c1017fd086cdfe53d8524e68c661c

Could you draft a man-pages patch for this interface
change, please? Or, failing that, a plain-text 
description that we can integrate into the man-page.

Thanks,

Michael

On 03/23/2016 10:33 AM, Wangnan (F) wrote:
> 
> 
> On 2016/3/23 17:16, Peter Zijlstra wrote:
>> On Mon, Mar 14, 2016 at 09:59:41AM +0000, Wang Nan wrote:
>>> Add new ioctl() to pause/resume ring-buffer output.
>>>
>>> In some situations we want to read from ring buffer only when we
>>> ensure nothing can write to the ring buffer during reading. Without
>>> this patch we have to turn off all events attached to this ring buffer
>>> to achieve this.
>>>
>>> This patch is for supporting overwrite ring buffer. Following
>>> commits will introduce new methods support reading from overwrite ring
>>> buffer. Before reading caller must ensure the ring buffer is frozen, or
>>> the reading is unreliable.
>>> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>>> index 1afe962..a3c1903 100644
>>> --- a/include/uapi/linux/perf_event.h
>>> +++ b/include/uapi/linux/perf_event.h
>>> @@ -401,6 +401,7 @@ struct perf_event_attr {
>>>   #define PERF_EVENT_IOC_SET_FILTER	_IOW('$', 6, char *)
>>>   #define PERF_EVENT_IOC_ID		_IOR('$', 7, __u64 *)
>>>   #define PERF_EVENT_IOC_SET_BPF		_IOW('$', 8, __u32)
>>> +#define PERF_EVENT_IOC_PAUSE_OUTPUT	_IOW('$', 9, __u32)
> 
> Glad to see you start to look at this patchset.
> 
> 
> 
>> Can you also do a patch to the man-pages?
>>
>>    http://man7.org/linux/man-pages/man2/perf_event_open.2.html
> 
> Sure.
> 
> I think I need to provide a patch for:
> 
>   http://git.kernel.org/cgit/docs/man-pages/man-pages.git
> 
> But which one should be the first? Shall we update man pages before
> this patch be merged by upstream? Or Michael and Vince will consider
> this problem?
> 
> Thank you.
> 
> 
> 


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/