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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
arch RISC-V updates for v5.3-rc4 2019-08-10 16:31:47 -07:00
block block, bfq: handle NULL return value by bfq_init_rq() 2019-08-08 07:31:50 -06:00
certs Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
crypto USB / PHY patches for 5.3-rc1 2019-07-11 15:40:06 -07:00
Documentation RISC-V updates for v5.3-rc4 2019-08-10 16:31:47 -07:00
drivers Bug fix for NTB MSI kernel compile warning 2019-08-11 10:13:53 -07:00
fs dax fixes v5.3-rc4 2019-08-11 13:15:10 -07:00
include Bugfixes (arm and x86) and cleanups. 2019-08-09 15:46:29 -07:00
init Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
ipc Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
kernel Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-10 15:48:02 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-06 17:11:59 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm mm/memremap: Fix reuse of pgmap instances with internal references 2019-08-09 14:16:15 -07:00
net net: dsa: sja1105: Fix memory leak on meta state machine error path 2019-08-06 14:37:02 -07:00
samples treewide: remove SPDX "WITH Linux-syscall-note" from kernel-space headers again 2019-07-25 11:05:10 +02:00
scripts kbuild: show hint if subdir-y/m is used to visit module Makefile 2019-08-10 01:45:31 +09:00
security selinux/stable-5.3 PR 20190801 2019-08-02 18:40:49 -07:00
sound sound fixes for 5.3-rc4 2019-08-09 09:21:27 -07:00
tools perf report: Prefer DWARF callstacks to LBR ones when captured both 2019-08-20 12:20:16 -03:00
usr kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test 2019-07-23 10:45:46 +02:00
virt KVM/arm fixes for 5.3, take #2 2019-08-09 16:53:50 +02:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig
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.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: Add compilation database file 2019-07-27 12:18:19 +09:00
.mailmap MAINTAINERS: Update my email address 2019-07-22 14:57:50 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Remove references to dead website. 2019-07-19 12:22:04 -07:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Char/misc fixes for 5.3-rc4 2019-08-10 12:24:20 -07:00
Makefile Linux 5.3-rc4 2019-08-11 13:26:41 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.