linux-kernel - Re: [PATCHv2 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder

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Date:	Wed, 18 Nov 2015 17:29:44 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Jiri Olsa <jolsa@...hat.com>
CC:	Jiri Olsa <jolsa@...nel.org>,
	Arnaldo Carvalho de Melo <acme@...nel.org>,
	lkml <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	"Peter Zijlstra" <peterz@...radead.org>,
	Ingo Molnar <mingo@...nel.org>,
	Namhyung Kim <namhyung@...nel.org>,
	Milian Wolff <milian.wolff@...b.com>
Subject: Re: [PATCHv2 2/3] perf tools: Add callchain order support for libunwind
 DWARF unwinder



On 2015/11/18 15:52, Jiri Olsa wrote:
> On Wed, Nov 18, 2015 at 12:13:08PM +0800, Wangnan (F) wrote:
>>
>> On 2015/11/17 23:05, Jiri Olsa wrote:
>>> From: Jiri Olsa <jolsa@...hat.com>
>>>
>>> As reported by Milian, currently for DWARF unwind (both libdw
>>> and libunwind) we display callchain in callee order only.
>>>
>>> Adding the support to follow callchain order setup to libunwind
>>> DWARF unwinder, so we could get following output for report:
>>>
>>>    $ perf record --call-graph dwarf ls
>>>    ...
>>>    $ perf report --no-children --stdio
>>>
>>>      39.26%  ls       libc-2.21.so      [.] __strcoll_l
>>>                   |
>>>                   ---__strcoll_l
>>>                      mpsort_with_tmp
>>>                      mpsort_with_tmp
>>>                      sort_files
>>>                      main
>>>                      __libc_start_main
>>>                      _start
>>>                      0
>>>
>>>    $ perf report -g caller --no-children --stdio
>>>      ...
>>>      39.26%  ls       libc-2.21.so      [.] __strcoll_l
>>>                   |
>>>                   ---0
>>>                      _start
>>>                      __libc_start_main
>>>                      main
>>>                      sort_files
>>>                      mpsort_with_tmp
>>>                      mpsort_with_tmp
>>>                      __strcoll_l
>>>
>>> Reported-by: Milian Wolff <milian.wolff@...b.com>
>>> Based-on-patch-by: Milian Wolff <milian.wolff@...b.com>
>>> Link: http://lkml.kernel.org/n/tip-lmtbeqm403f3luw4jkjevsi5@git.kernel.org
>>> Signed-off-by: Jiri Olsa <jolsa@...nel.org>
>>> ---
>>>   tools/perf/util/unwind-libunwind.c | 47 ++++++++++++++++++++++++--------------
>>>   1 file changed, 30 insertions(+), 17 deletions(-)
>>>
>>> diff --git a/tools/perf/util/unwind-libunwind.c b/tools/perf/util/unwind-libunwind.c
>>> index 0ae8844fe7a6..705e1c19f1ea 100644
>>> --- a/tools/perf/util/unwind-libunwind.c
>>> +++ b/tools/perf/util/unwind-libunwind.c
>> [SNIP]
>>
>>> -		unw_get_reg(&c, UNW_REG_IP, &ip);
>>> -		ret = ip ? entry(ip, ui->thread, cb, arg) : 0;
>> In original code if ip == 0 entry() won't be called.
>>
>>> +		if (callchain_param.order == ORDER_CALLER)
>>> +			j = max_stack - i - 1;
>>> +		ret = entry(ips[j], ui->thread, cb, arg);
> ouch.. the intention was not to breake current behaviour ;-)
>
> v2 is attached, it's also in perf/callchain_2 branch
>
> thanks,
> jirka
>
>
> ---
> As reported by Milian, currently for DWARF unwind (both libdw
> and libunwind) we display callchain in callee order only.
>
> Adding the support to follow callchain order setup to libunwind
> DWARF unwinder, so we could get following output for report:
>
>    $ perf record --call-graph dwarf ls
>    ...
>    $ perf report --no-children --stdio
>
>      39.26%  ls       libc-2.21.so      [.] __strcoll_l
>                   |
>                   ---__strcoll_l
>                      mpsort_with_tmp
>                      mpsort_with_tmp
>                      sort_files
>                      main
>                      __libc_start_main
>                      _start
>                      0
>
>    $ perf report -g caller --no-children --stdio
>      ...
>      39.26%  ls       libc-2.21.so      [.] __strcoll_l
>                   |
>                   ---0
>                      _start
>                      __libc_start_main
>                      main
>                      sort_files
>                      mpsort_with_tmp
>                      mpsort_with_tmp
>                      __strcoll_l
>
> Reported-by: Milian Wolff <milian.wolff@...b.com>
> Based-on-patch-by: Milian Wolff <milian.wolff@...b.com>
> Link: http://lkml.kernel.org/n/tip-lmtbeqm403f3luw4jkjevsi5@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>

This time behavior is not changed. Thank you.

Tested-by: Wang Nan <wangnan0@...wei.com>


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