[RFC/PATCHSET 0/5] perf tools: Support deferred user callchains (v2)

[Namhyung Kim <namhyung@kernel.org>]

Hello,

This is a counterpart for Josh's kernel change v2 [1] to support deferred
user callchains.  The change is transparent and users should not notice
anything with the deferred callchains.

  $ perf record -g sleep 1

I added --[no-]merge-callchains option to control output of perf script.
You can verify it has the deferred callchains like this:

  $ perf script --no-merge-callchains
  perf     801 [000]    18.031793:          1 cycles:P:
          ffffffff91a14c36 __intel_pmu_enable_all.isra.0+0x56 ([kernel.kallsyms])
          ffffffff91d373e9 perf_ctx_enable+0x39 ([kernel.kallsyms])
          ffffffff91d36af7 event_function+0xd7 ([kernel.kallsyms])
          ffffffff91d34222 remote_function+0x42 ([kernel.kallsyms])
          ffffffff91c1ebe1 generic_exec_single+0x61 ([kernel.kallsyms])
          ffffffff91c1edac smp_call_function_single+0xec ([kernel.kallsyms])
          ffffffff91d37a9d event_function_call+0x10d ([kernel.kallsyms])
          ffffffff91d33557 perf_event_for_each_child+0x37 ([kernel.kallsyms])
          ffffffff91d47324 _perf_ioctl+0x204 ([kernel.kallsyms])
          ffffffff91d47c43 perf_ioctl+0x33 ([kernel.kallsyms])
          ffffffff91e2f216 __x64_sys_ioctl+0x96 ([kernel.kallsyms])
          ffffffff9265f1ae do_syscall_64+0x9e ([kernel.kallsyms])
          ffffffff92800130 entry_SYSCALL_64+0xb0 ([kernel.kallsyms])

  perf     801 [000]    18.031814: DEFERRED CALLCHAIN
                  7fb5fc22034b __GI___ioctl+0x3b (/usr/lib/x86_64-linux-gnu/libc.so.6)

  ...

When the callchain is merged (it's the default) it'd look like below:

  $ perf script
  perf     801 [000]    18.031793:          1 cycles:P:
          ffffffff91a14c36 __intel_pmu_enable_all.isra.0+0x56 ([kernel.kallsyms])
          ffffffff91d373e9 perf_ctx_enable+0x39 ([kernel.kallsyms])
          ffffffff91d36af7 event_function+0xd7 ([kernel.kallsyms])
          ffffffff91d34222 remote_function+0x42 ([kernel.kallsyms])
          ffffffff91c1ebe1 generic_exec_single+0x61 ([kernel.kallsyms])
          ffffffff91c1edac smp_call_function_single+0xec ([kernel.kallsyms])
          ffffffff91d37a9d event_function_call+0x10d ([kernel.kallsyms])
          ffffffff91d33557 perf_event_for_each_child+0x37 ([kernel.kallsyms])
          ffffffff91d47324 _perf_ioctl+0x204 ([kernel.kallsyms])
          ffffffff91d47c43 perf_ioctl+0x33 ([kernel.kallsyms])
          ffffffff91e2f216 __x64_sys_ioctl+0x96 ([kernel.kallsyms])
          ffffffff9265f1ae do_syscall_64+0x9e ([kernel.kallsyms])
          ffffffff92800130 entry_SYSCALL_64+0xb0 ([kernel.kallsyms])
                  7fb5fc22034b __GI___ioctl+0x3b (/usr/lib/x86_64-linux-gnu/libc.so.6)

  ...

Notice that the last line and it has the __GI___ioctl in the same
callchain.  It should work with other tools like perf report.

The code is available at 'perf/defer-callchain-v2' branch in
https://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git

Thanks,
Namhyung

[1] https://lore.kernel.org/lkml/cover.1726268190.git.jpoimboe@kernel.org


Namhyung Kim (5):
  perf tools: Sync UAPI perf_event.h header
  perf tools: Minimal DEFERRED_CALLCHAIN support
  perf record: Enable defer_callchain for user callchains
  perf script: Display PERF_RECORD_CALLCHAIN_DEFERRED
  perf tools: Merge deferred user callchains

 tools/include/uapi/linux/perf_event.h     | 21 +++++-
 tools/lib/perf/include/perf/event.h       |  7 ++
 tools/perf/Documentation/perf-script.txt  |  5 ++
 tools/perf/builtin-script.c               | 92 +++++++++++++++++++++++
 tools/perf/util/callchain.c               | 24 ++++++
 tools/perf/util/callchain.h               |  3 +
 tools/perf/util/event.c                   |  1 +
 tools/perf/util/evlist.c                  |  1 +
 tools/perf/util/evlist.h                  |  1 +
 tools/perf/util/evsel.c                   | 32 +++++++-
 tools/perf/util/evsel.h                   |  1 +
 tools/perf/util/machine.c                 |  1 +
 tools/perf/util/perf_event_attr_fprintf.c |  1 +
 tools/perf/util/sample.h                  |  3 +-
 tools/perf/util/session.c                 | 78 +++++++++++++++++++
 tools/perf/util/tool.c                    |  2 +
 tools/perf/util/tool.h                    |  4 +-
 17 files changed, 273 insertions(+), 4 deletions(-)

-- 
2.46.0.792.g87dc391469-goog