linux-kernel - Re: [PATCH V3 1/6] perf/core: Adding PMU driver specific configuration

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Message-ID: <CANLsYkwz1aCmsBbtZXQK3_B-T6cVBP1UYV9cqbKiNSmdrhUuFQ@mail.gmail.com>
Date:	Wed, 10 Aug 2016 17:07:13 -0600
From:	Mathieu Poirier <mathieu.poirier@...aro.org>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>, jolsa@...nel.org,
	Ingo Molnar <mingo@...hat.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Vince Weaver <vince@...ter.net>,
	"Michael Kerrisk (man-pages)" <mtk.manpages@...il.com>
Subject: Re: [PATCH V3 1/6] perf/core: Adding PMU driver specific configuration

On 5 August 2016 at 09:53, Peter Zijlstra <peterz@...radead.org> wrote:
> On Fri, Aug 05, 2016 at 09:35:05AM -0600, Mathieu Poirier wrote:
>> On 4 August 2016 at 10:58, Peter Zijlstra <peterz@...radead.org> wrote:
>> > On Thu, Jul 28, 2016 at 03:42:18PM -0600, Mathieu Poirier wrote:
>> >> This patch somewhat mimics the work done on address filters to
>> >> add the infrastructure needed to pass PMU specific HW
>> >> configuration to the driver before a session starts.
>> >>
>> >> Signed-off-by: Mathieu Poirier <mathieu.poirier@...aro.org>
>> >
>> >> diff --git a/include/uapi/linux/perf_event.h b/include/uapi/linux/perf_event.h
>> >> index c66a485a24ac..90fbc5fd3925 100644
>> >> --- a/include/uapi/linux/perf_event.h
>> >> +++ b/include/uapi/linux/perf_event.h
>> >> @@ -407,6 +407,7 @@ struct perf_event_attr {
>> >>  #define PERF_EVENT_IOC_ID            _IOR('$', 7, __u64 *)
>> >>  #define PERF_EVENT_IOC_SET_BPF               _IOW('$', 8, __u32)
>> >>  #define PERF_EVENT_IOC_PAUSE_OUTPUT  _IOW('$', 9, __u32)
>> >> +#define PERF_EVENT_IOC_SET_DRV_CONFIGS       _IOW('$', 10, char *)
>> >
>> > Please also do a manpages patch.
>>
>> Patch 3/6 in this set documents the new option
>> (tools/perf/Documentation/perf-record.tx).  Is this what you were
>> looking for?  If not please expand on the information you want to see
>> added add and where.
>
> Since you add an IOCTL (with preferably more structure than present in
> this patch, see the other email) this needs to be documented in the
> syscall manpage.
>
>   http://git.kernel.org/cgit/docs/man-pages/man-pages.git/tree/man2/perf_event_open.2
>
>   http://www.man7.org/linux/man-pages/man2/perf_event_open.2.html

After a little bit of digging around I understand that manpages have
to be written _after_ the new ioctl call has been added - at least
that's what I deduce when looking at what Vince Weaver did for the BPF
support:

commit b0f7b411bed0505937f0f51d6499d0c6c56f4b8c
Author: Vince Weaver <vincent.weaver@...ne.edu>
Date:   Thu Jul 23 13:10:21 2015 -0400

    perf_event_open.2: 4.1 PERF_EVENT_IOC_SET_BPF support

    This manpage patch relates to the addition of the
    PERF_EVENT_IOC_SET_BPF ioctl in the following commit:

        commit 2541517c32be2531e0da59dfd7efc1ce844644f5
        Author: Alexei Starovoitov <ast@...mgrid.com>

        tracing, perf: Implement BPF programs attached to kprobes

        Signed-off-by: Alexei Starovoitov <ast@...mgrid.com>
        Reviewed-by: Steven Rostedt <rostedt@...dmis.org>
        Reviewed-by: Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
        Cc: Andrew Morton <akpm@...ux-foundation.org>
        Cc: Arnaldo Carvalho de Melo <acme@...radead.org>
        Cc: Arnaldo Carvalho de Melo <acme@...hat.com>
        Cc: Daniel Borkmann <daniel@...earbox.net>
        Cc: David S. Miller <davem@...emloft.net>
        Cc: Jiri Olsa <jolsa@...hat.com>
        Cc: Linus Torvalds <torvalds@...ux-foundation.org>
        Cc: Namhyung Kim <namhyung@...nel.org>
        Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
        Cc: Peter Zijlstra <peterz@...radead.org>
        Link: http://lkml.kernel.org/r/1427312966-8434-4-git-send-email-ast@plumgrid.com
        Signed-off-by: Ingo Molnar <mingo@...nel.org>

    Signed-off-by: Vince Weaver <vincent.weaver@...ne.edu>
    Signed-off-by: Michael Kerrisk <mtk.manpages@...il.com>

Am I correct here or you want to proceed differently?

Thanks for the guidance,
Mathieu