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From: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: linux-kernel@vger.kernel.org, acme@kernel.org,
	"Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
	linuxppc-dev@lists.ozlabs.org, mark@klomp.org
Subject: Re: [PATCH v2] perf: libdw support for powerpc [ping]
Date: Mon, 12 Jun 2017 17:28:37 +0530	[thread overview]
Message-ID: <593E81ED.8060606@linux.vnet.ibm.com> (raw)
In-Reply-To: <a44cf3bd-e868-a8d5-4518-2bea76be7f8f@redhat.com>

Hi Paolo,

Thanks for the patch and really sorry for being late. I was quite busy
with few other things.

On Friday 09 June 2017 06:00 PM, Paolo Bonzini wrote:
>
> On 01/06/2017 12:24, Paolo Bonzini wrote:
>> Porting PPC to libdw only needs an architecture-specific hook to move
>> the register state from perf to libdw.
>>
>> The ARM and x86 architectures already use libdw, and it is useful to
>> have as much common code for the unwinder as possible.  Mark Wielaard
>> has contributed a frame-based unwinder to libdw, so that unwinding works
>> even for binaries that do not have CFI information.  In addition,
>> libunwind is always preferred to libdw by the build machinery so this
>> cannot introduce regressions on machines that have both libunwind and
>> libdw installed.
>>
>> Cc: acme@kernel.org
>> Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
>> Cc: Ravi Bangoria <ravi.bangoria@linux.vnet.ibm.com>
>> Cc: linuxppc-dev@lists.ozlabs.org
>> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
>> ---
>> 	v1->v2: fix for 4.11->4.12 changes
> Ravi, Naveen, any reviews?

So, I tested this patch along with Mark's patch[1] on elfutils an looks
like it's not working. Steps on what I did:

After applying Mark's patch on upstream elfutils:

  $ aclocal
  $ autoheader
  $ autoconf
  $ automake --add-missing
  $ ./configure
  $ make
  $ make install DESTDIR=/home/ravi/elfutils-git

After applying your patch on upstream perf:

  $ make
  $ ./perf record --call-graph=dwarf ls
  $ LD_LIBRARY_PATH=/home/ravi/elfutils-git/usr/local/lib:\
    /home/ravi/elfutils-git/usr/local/lib/elfutils/:$LD_LIBRARY_PATH \
    ./perf script

    ls 44159  1800.878468:     191408 cycles:u:

    ls 44159  1800.878673:     419356 cycles:u:
                       8a97c hpte_need_flush (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       835f4 flush_hash_page (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       8acec hpte_need_flush (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      3468f4 ptep_clear_flush (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      328b10 wp_page_copy (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      32ebe4 do_wp_page (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      33434c __handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      335040 handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       7bf94 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       1a4f8 handle_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)

    ls 44159  1800.878961:     430876 cycles:u:

    ls 44159  1800.879195:     423785 cycles:u:

    ls 44159  1800.879360:     427359 cycles:u:

Here I don't see userspace callchain getting unwound. Please let me know
if I'm doing anything wrong. Same perf.data with libunwind:

    ls 44159  1800.878468:     191408 cycles:u:
                       20380 _dl_sysdep_start (/usr/lib64/ld-2.17.so)
                        1c7f _dl_start_final (/usr/lib64/ld-2.17.so)
                        5ce7 _dl_start (/usr/lib64/ld-2.17.so)
                        1937 _start (/usr/lib64/ld-2.17.so)

    ls 44159  1800.878673:     419356 cycles:u:
                       8a97c hpte_need_flush (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       835f4 flush_hash_page (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       8acec hpte_need_flush (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      3468f4 ptep_clear_flush (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      328b10 wp_page_copy (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      32ebe4 do_wp_page (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      33434c __handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                      335040 handle_mm_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       7bf94 do_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                       1a4f8 handle_page_fault (/usr/lib/debug/lib/modules/4.11.0-3.el7.ppc64le/vmlinux)
                        7cd4 _dl_map_object_from_fd (/usr/lib64/ld-2.17.so)
                        b24b _dl_map_object (/usr/lib64/ld-2.17.so)
                       12b3b openaux (/usr/lib64/ld-2.17.so)
                       159bf _dl_catch_error (/usr/lib64/ld-2.17.so)
                       13323 _dl_map_object_deps (/usr/lib64/ld-2.17.so)
                        3feb dl_main (/usr/lib64/ld-2.17.so)
                       2045b _dl_sysdep_start (/usr/lib64/ld-2.17.so)
                        1c7f _dl_start_final (/usr/lib64/ld-2.17.so)
                        5ce7 _dl_start (/usr/lib64/ld-2.17.so)
                        1937 _start (/usr/lib64/ld-2.17.so)

    ls 44159  1800.878961:     430876 cycles:u:
                        dcb8 check_match.10245 (/usr/lib64/ld-2.17.so)
                        e55b do_lookup_x (/usr/lib64/ld-2.17.so)
                        e8d7 _dl_lookup_symbol_x (/usr/lib64/ld-2.17.so)
                       10493 _dl_relocate_object (/usr/lib64/ld-2.17.so)
                        4cf7 dl_main (/usr/lib64/ld-2.17.so)
                       2045b _dl_sysdep_start (/usr/lib64/ld-2.17.so)
                        1c7f _dl_start_final (/usr/lib64/ld-2.17.so)
                        5ce7 _dl_start (/usr/lib64/ld-2.17.so)
                        1937 _start (/usr/lib64/ld-2.17.so)

    ls 44159  1800.879195:     423785 cycles:u:
                       960a0 malloc (/usr/lib64/libc-2.17.so)
                       32a53 _nl_intern_locale_data (/usr/lib64/libc-2.17.so)
                       3337f _nl_load_locale_from_archive (/usr/lib64/libc-2.17.so)
                       323b3 _nl_find_locale (/usr/lib64/libc-2.17.so)
                       31b93 setlocale (/usr/lib64/libc-2.17.so)
                        2a8b _init (/usr/bin/ls)
                       2497f generic_start_main.isra.0 (/usr/lib64/libc-2.17.so)
                       24b73 __libc_start_main (/usr/lib64/libc-2.17.so)

    ls 44159  1800.879360:     427359 cycles:u:
                       a42b8 get_next_seq (/usr/lib64/libc-2.17.so)
                       a54ff __strcoll_l (/usr/lib64/libc-2.17.so)


[1] https://sourceware.org/ml/elfutils-devel/2017-q2/msg00223.html

  reply	other threads:[~2017-06-12 11:58 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-01 10:24 [PATCH v2] perf: libdw support for powerpc Paolo Bonzini
2017-06-09 12:30 ` [PATCH v2] perf: libdw support for powerpc [ping] Paolo Bonzini
2017-06-12 11:58   ` Ravi Bangoria [this message]
2017-06-13 11:44     ` Mark Wielaard
2017-06-13 15:55       ` Ravi Bangoria
2017-06-15  8:46         ` Milian Wolff
2017-06-15 11:16           ` Mark Wielaard
2017-06-16  4:21             ` Ravi Bangoria
2017-06-21  1:06             ` Arnaldo Carvalho de Melo
2017-06-21  1:31               ` Mark Wielaard
2017-06-21  1:07           ` Arnaldo Carvalho de Melo
2017-06-21  8:16             ` Milian Wolff
2017-06-21 12:48               ` Arnaldo Carvalho de Melo
2017-06-21 14:19                 ` Milian Wolff
2017-06-21 14:33                   ` Arnaldo Carvalho de Melo
2017-06-15 12:13 ` [PATCH v2] perf: libdw support for powerpc Jiri Olsa
2017-06-20 21:53 ` Arnaldo Carvalho de Melo

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