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Subject: Re: [PATCH 1/5] perf core: Introduce new ioctl options to pause and
 resume ring buffer
To: Peter Zijlstra <peterz@infradead.org>
References: <1457949585-191064-1-git-send-email-wangnan0@huawei.com>
 <1457949585-191064-2-git-send-email-wangnan0@huawei.com>
 <20160323091654.GV6344@twins.programming.kicks-ass.net>
CC: <mingo@redhat.com>, <linux-kernel@vger.kernel.org>,
        He Kuang <hekuang@huawei.com>, Alexei Starovoitov <ast@kernel.org>,
        "Arnaldo Carvalho de Melo" <acme@redhat.com>,
        Brendan Gregg <brendan.d.gregg@gmail.com>,
        "Jiri Olsa" <jolsa@kernel.org>,
        Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>,
        Namhyung Kim <namhyung@kernel.org>, Zefan Li <lizefan@huawei.com>,
        <pi3orama@163.com>, Vince Weaver <vince@deater.net>,
        "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
From: "Wangnan (F)" <wangnan0@huawei.com>
Message-ID: <56F26301.3010100@huawei.com>
Date: Wed, 23 Mar 2016 17:33:53 +0800
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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.