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Groups > linux.kernel > #1271841
| From | "Wangnan (F)" <wangnan0@huawei.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder |
| Date | 2015-11-18 05:20 +0100 |
| Message-ID | <qw2nU-6d6-13@gated-at.bofh.it> (permalink) |
| References | <qvQ3o-6Fs-9@gated-at.bofh.it> <qvQ3o-6Fs-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On 2015/11/17 23:05, Jiri Olsa wrote:
> From: Jiri Olsa <jolsa@redhat.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@kdab.com>
> Based-on-patch-by: Milian Wolff <milian.wolff@kdab.com>
> Link: http://lkml.kernel.org/n/tip-lmtbeqm403f3luw4jkjevsi5@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.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);
But in new code event if ips[j] == 0 an entry will be built, which causes
a behavior changes user noticable:
Before this patch:
# perf report --no-children --stdio --call-graph=callee
...
3.38% a.out a.out [.] funcc
|
---funcc
|
--2.70%-- funcb
funca
main
__libc_start_main
_start
After this patch:
# perf report --no-children --stdio --call-graph=callee
...
3.38% a.out a.out [.] funcc
|
---funcc
|
|--2.70%-- funcb
| funca
| main
| __libc_start_main
| _start
|
--0.68%-- 0
I'm not sure whether we can regard this behavior changing as a bugfix? I
think
there may be some reason the original code explicitly avoid creating an '0'
entry.
Then I tried to find why perf can't get call frame on my case, and
I guess there's something wrong whe dealing with 'call' command, because
the instruction on it I can't get callchain from libunwind is a 'callq':
...
4005bf: be 00 00 00 00 mov $0x0,%esi
4005c4: 48 89 c7 mov %rax,%rdi
4005c7: e8 74 fe ff ff callq 400440 <gettimeofday@plt>
us2 = tv2.tv_sec * 1000000 + tv2.tv_usec;
4005cc: 48 8b 04 24 mov (%rsp),%rax
...
But this is another problem, we can discuss it in a new thread.
Thank you.
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[PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Jiri Olsa <jolsa@kernel.org> - 2015-11-17 16:10 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 05:20 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Namhyung Kim <namhyung@kernel.org> - 2015-11-18 06:50 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 08:40 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Namhyung Kim <namhyung@kernel.org> - 2015-11-22 16:30 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Jiri Olsa <jolsa@redhat.com> - 2015-11-18 09:30 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Jiri Olsa <jolsa@redhat.com> - 2015-11-18 09:30 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Namhyung Kim <namhyung@gmail.com> - 2015-11-18 10:30 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Jiri Olsa <jolsa@redhat.com> - 2015-11-18 09:00 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 09:10 +0100
Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Jiri Olsa <jolsa@redhat.com> - 2015-11-18 09:20 +0100
[PATCHv2 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder Jiri Olsa <jolsa@redhat.com> - 2015-11-18 09:00 +0100
Re: [PATCHv2 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder "Wangnan (F)" <wangnan0@huawei.com> - 2015-11-18 10:50 +0100
[tip:perf/core] perf callchain: Add order support for libunwind DWARF unwinder tip-bot for Jiri Olsa <tipbot@zytor.com> - 2015-11-26 09:20 +0100
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