Alexey Budankov 10ccbc1cc0 perf report: Prefer DWARF callstacks to LBR ones when captured both
Display DWARF based callchains when the perf.data file contains raw thread
stack data as LBR callstack data.

Commiter testing:

This changes the output from the branch stack based one, i.e. without
this patch, for the same file as in the previous csets:

  # perf report --stdio
  # To display the perf.data header info, please use --header/--header-only options.
  #
  # Total Lost Samples: 0
  #
  # Samples: 13  of event 'cycles'
  # Event count (approx.): 13
  #
  # Overhead  Command  Source Shared Object  Source Symbol                Target Symbol                              Basic Block Cycles
  # ........  .......  ....................  ...........................  .........................................  ..................
  #
       7.69%  ls       libpthread-2.29.so    [.] _init                    [.] __pthread_initialize_minimal_internal  6827
       7.69%  ls       ld-2.29.so            [k] _start                   [k] _dl_start                              -
       7.69%  ls       ld-2.29.so            [.] _dl_start_user           [.] _dl_init                               -24790
       7.69%  ls       ld-2.29.so            [k] _dl_start                [k] _dl_sysdep_start                       278
       7.69%  ls       ld-2.29.so            [k] dl_main                  [k] _dl_map_object_deps                    15581
       7.69%  ls       ld-2.29.so            [k] open_verify.constprop.0  [k] lseek64                                4228
       7.69%  ls       ld-2.29.so            [k] _dl_map_object           [k] open_verify.constprop.0                55
       7.69%  ls       ld-2.29.so            [k] openaux                  [k] _dl_map_object                         67
       7.69%  ls       ld-2.29.so            [k] _dl_map_object_deps      [k] 0x00007f441b57c090                     112
       7.69%  ls       ld-2.29.so            [.] call_init.part.0         [.] _init                                  334
       7.69%  ls       ld-2.29.so            [.] _dl_init                 [.] call_init.part.0                       383
       7.69%  ls       ld-2.29.so            [k] _dl_sysdep_start         [k] dl_main                                45
       7.69%  ls       ld-2.29.so            [k] _dl_catch_exception      [k] openaux                                116

  #
  # (Tip: For memory address profiling, try: perf mem record / perf mem report)
  #

To the one that shows call chains:

  # perf report --stdio
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 10  of event 'cycles'
  # Event count (approx.): 3204047
  #
  # Children      Self  Command  Shared Object       Symbol
  # ........  ........  .......  ..................  .........................................
  #
      55.01%     0.00%  ls       [kernel.vmlinux]    [k] entry_SYSCALL_64_after_hwframe
              |
              ---entry_SYSCALL_64_after_hwframe
                 do_syscall_64
                 |
                  --16.01%--__x64_sys_execve
                            __do_execve_file.isra.0
                            search_binary_handler
                            load_elf_binary
                            elf_map
                            vm_mmap_pgoff
                            do_mmap
                            mmap_region
                            perf_event_mmap
                            perf_iterate_sb
                            perf_iterate_ctx
                            perf_event_mmap_output
                            perf_output_copy
                            memcpy_erms

      55.01%    39.00%  ls       [kernel.vmlinux]    [k] do_syscall_64
              |
              |--39.00%--0xffffffffffffffff
              |          _dl_map_object
              |          open_verify.constprop.0
              |          __lseek64 (inlined)
              |          entry_SYSCALL_64_after_hwframe
              |          do_syscall_64
              |
               --16.01%--do_syscall_64
                         __x64_sys_execve
                         __do_execve_file.isra.0
                         search_binary_handler
                         load_elf_binary
                         elf_map
                         vm_mmap_pgoff
                         do_mmap
                         mmap_region
                         perf_event_mmap
                         perf_iterate_sb
                         perf_iterate_ctx
                         perf_event_mmap_output
                         perf_output_copy
                         memcpy_erms

      42.95%    42.95%  ls       libpthread-2.29.so  [.] __pthread_initialize_minimal_internal
              |
              ---_init
                 __pthread_initialize_minimal_internal

      42.95%     0.00%  ls       libpthread-2.29.so  [.] _init
              |
              ---_init
                 __pthread_initialize_minimal_internal

  <SNIP>

  #
  # (Tip: Profiling branch (mis)predictions with: perf record -b / perf report)
  #
  #

The branch stack view be explicitely selected using:

  # perf report -h branch-stack

   Usage: perf report [<options>]

      -b, --branch-stack    use branch records for per branch histogram filling

  #

I.e. after this patch:

  # perf report -b --stdio
  # To display the perf.data header info, please use --header/--header-only options.
  #
  #
  # Total Lost Samples: 0
  #
  # Samples: 13  of event 'cycles'
  # Event count (approx.): 13
  #
  # Overhead  Command  Source Shared Object  Source Symbol                Target Symbol                              Basic Block Cycles
  # ........  .......  ....................  ...........................  .........................................  ..................
  #
       7.69%  ls       libpthread-2.29.so    [.] _init                    [.] __pthread_initialize_minimal_internal  6827
       7.69%  ls       ld-2.29.so            [k] _start                   [k] _dl_start                              -
       7.69%  ls       ld-2.29.so            [.] _dl_start_user           [.] _dl_init                               -24790
       7.69%  ls       ld-2.29.so            [k] _dl_start                [k] _dl_sysdep_start                       278
       7.69%  ls       ld-2.29.so            [k] dl_main                  [k] _dl_map_object_deps                    15581
       7.69%  ls       ld-2.29.so            [k] open_verify.constprop.0  [k] lseek64                                4228
       7.69%  ls       ld-2.29.so            [k] _dl_map_object           [k] open_verify.constprop.0                55
       7.69%  ls       ld-2.29.so            [k] openaux                  [k] _dl_map_object                         67
       7.69%  ls       ld-2.29.so            [k] _dl_map_object_deps      [k] 0x00007f441b57c090                     112
       7.69%  ls       ld-2.29.so            [.] call_init.part.0         [.] _init                                  334
       7.69%  ls       ld-2.29.so            [.] _dl_init                 [.] call_init.part.0                       383
       7.69%  ls       ld-2.29.so            [k] _dl_sysdep_start         [k] dl_main                                45
       7.69%  ls       ld-2.29.so            [k] _dl_catch_exception      [k] openaux                                116

  #
  # (Tip: Show current config key-value pairs: perf config --list)
  #
  #

Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/ccbd9583-82f4-dec5-7e84-64bf56e351fb@linux.intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2019-08-20 12:20:16 -03:00
2019-07-22 14:57:50 +01:00
2019-07-19 12:22:04 -07:00
2019-08-11 13:26:41 -07:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Description
No description provided
Readme 7.9 GiB
Languages
C 97.7%
Assembly 1.6%
Makefile 0.3%
Perl 0.1%