linux-kernel - Re: [PATCH v10 04/10] perf evlist: Introduce aux evlist

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Date:	Thu, 23 Jun 2016 09:15:02 -0500
From:	Nilay Vaish <nilayvaish@...il.com>
To:	Wang Nan <wangnan0@...wei.com>
Cc:	acme@...nel.org, Linux Kernel list <linux-kernel@...r.kernel.org>,
	pi3orama@....com, He Kuang <hekuang@...wei.com>,
	Jiri Olsa <jolsa@...nel.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Zefan Li <lizefan@...wei.com>
Subject: Re: [PATCH v10 04/10] perf evlist: Introduce aux evlist

On 23 June 2016 at 00:27, Wang Nan <wangnan0@...wei.com> wrote:
> An auxiliary evlist is created by perf_evlist__new_aux() using an
> existing evlist as its parent. An auxiliary evlist can have its own
> 'struct perf_mmap', but can't have any other data. User should use its
> parent instead when accessing other data.
>
> Auxiliary evlists are containers of 'struct perf_mmap'. It is introduced
> to allow its parent evlist to map different events into separated mmaps.
>
> Following commits create an auxiliary evlist for overwritable
> events, because overwritable events need a read only and backwards ring
> buffer, which is different from normal events.
>
> To achieve this goal, this patch carefully changes 'evlist' to
> 'evlist->parent' in all functions in the path of 'perf_evlist__mmap_ex',
> except 'evlist->mmap' related operations, to make sure all evlist
> modifications (like pollfd and event id hash tables) goes to original
> evlist.
>
> A 'evlist->parent' pointer is added to 'struct perf_evlist' and points to
> the evlist itself for normal evlists.
>
> Children of one evlist are linked into it so one can find all children
> from its parent.
>
> To avoid potential complexity, forbid creating aux evlist from another
> aux evlist.
>
> Improve perf_evlist__munmap_filtered(), so when recording, if an event
> is terminated, unmap mmaps, from parent and children.
>
> Signed-off-by: Wang Nan <wangnan0@...wei.com>
> Cc: He Kuang <hekuang@...wei.com>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Zefan Li <lizefan@...wei.com>
> Cc: pi3orama@....com
> ---
>  tools/perf/util/evlist.c | 49 +++++++++++++++++++++++++++++++++++++-----------
>  tools/perf/util/evlist.h | 12 ++++++++++++
>  2 files changed, 50 insertions(+), 11 deletions(-)


Wang, thanks for making the change.  The patch seems perfectly fine to me.

--
Nilay