linux-kernel - Re: [PATCH 4/3] perf tools: Add callchain order support for libdw DWARF unwinder

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Date:	Thu, 19 Nov 2015 20:10:45 +0800
From:	"Wangnan (F)" <wangnan0@...wei.com>
To:	Jiri Olsa <jolsa@...hat.com>, Jiri Olsa <jolsa@...nel.org>
CC:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Jan Kratochvil <jkratoch@...hat.com>,
	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: [PATCH 4/3] perf tools: Add callchain order support for libdw
 DWARF unwinder



On 2015/11/19 19:22, Jiri Olsa wrote:
> On Tue, Nov 17, 2015 at 04:05:36PM +0100, Jiri Olsa wrote:
>
> SNIP
>
>> Tested on x86_64. The change is in generic code only,
>> so it should not affect other archs. Still it would be
>> nice to have some confirmation.. Wang Nan? ;-)
>>
>> It'd be nice to have this for libdw unwind as well,
>> but it looks like it's out of reach for perf code.. Jan?
>>
>> Also available in:
>>    git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
>>    perf/callchain_1
> adding also libdw support.. test with 'make NO_LIBUNWIND=1'
>
> Also available in:
>    git://git.kernel.org/pub/scm/linux/kernel/git/jolsa/perf.git
>    perf/callchain_3
>
> 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 libdw
> DWARF unwinder, so we could get following output for report:
>
>    $ perf record --call-graph dwarf ls
>    ...
>
>    $ perf report --no-children --stdio
>
>      13.63%  ls       [kernel.vmlinux]  [k] __rb_insert_augmented
>                   |
>                   ---__rb_insert_augmented
>                      __vma_link_rb
>                      vma_link
>                      do_brk
>                      vm_brk
>                      load_elf_binary
>                      search_binary_handler
>                      do_execveat_common.isra.29
>                      sys_execve
>                      return_from_execve
>
>    $ perf report --stdio --no-children -g caller
>
>      13.63%  ls       [kernel.vmlinux]  [k] __rb_insert_augmented
>                   |
>                   ---return_from_execve
>                      sys_execve
>                      do_execveat_common.isra.29
>                      search_binary_handler
>                      load_elf_binary
>                      vm_brk
>                      do_brk
>                      vma_link
>                      __vma_link_rb
>                      __rb_insert_augmented
>
> Reported-by: Milian Wolff <milian.wolff@...b.com>
> Link: http://lkml.kernel.org/n/tip-zk99ay9s71whl9qd9if28u8z@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@...nel.org>

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

And I suggest you put a user space call graph to the commit message
to show the result of this patch. What you show now is not related
to this patch, right?

In addition, just for your information, I find libdw can unwind call
chain I described yesterday in [1].

Thank you.

[1] https://lkml.kernel.org/g/564C26C4.2040603@huawei.com

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