[PATCH v5 0/7] perf/sdt: Directly record SDT events with 'perf record'

[Ravi Bangoria]

All events from 'perf list', except SDT events, can be directly recorded
with 'perf record'. But, the flow is little different for SDT events.
Probe point for SDT event needs to be created using 'perf probe' before
recording it using 'perf record'.

As suggested by Ingo[1], it's better to make this process simple by
creating probe point automatically with 'perf record' for SDT events.

Features:
  - Allow both 'perf probe' and 'perf record' on sdt events without
    changing current functionality.

  - Event starting with 'sdt_' or '%' will be considered as SDT event.

  - Always prioritize events from uprobe_events by first checking if
    event exists with exact name. If not found and user has used
    pattern, again try to find pattern matching entries from
    uprobe_events. If found use them. If not, lookup into probe-cache.
    If events found from probe-cache, again check if any event exists
    in uprobe_events by matching filepath+address, as it might exists
    in uprobe_events but with different name. Reuse those events which
    exists in uprobe_events and create new entries for missing one.
    Also maintain list for new entries being created and at the end
    of the session, delete them.

  - Show various warnings/hints to help user understand _which_ events
    are being recorded and _why_. For ex,

    When multiple events of same name found and all are being recorded:

      $ sudo ./perf record -a -e sdt_libpthread:mutex_entry
        Warning: Recording on 2 occurrences of sdt_libpthread:mutex_entry

    Events being reused from uprobe_events is listed as 'name addr@file'
    followed by hint on how to delete them:

      $ sudo ./perf record -a -e sdt_libpthread:mutex_entry
        Matching event(s) from uprobe_events:
          sdt_libpthread:mutex_entry  0x9ddb@/usr/lib64/libpthread-2.24.so
        Use 'perf probe -d <event>' to delete event(s).

    If number of events found from cache is not equal to number of events
    being recorded:

      $ sudo ./perf record -a -e sdt_libpthread:mutex_entry
        Warning: Found 2 events from probe-cache with name 'sdt_libpthread:mutex_entry'.
                 Since 1 probe point already exists, recording only it.
        Hint: Please use 'perf probe -d sdt_libpthread:mutex_entry' to allow record on all events.

  - If all events found from probe-cache are not present in uprobe_events,
    and user has used pattern to specify event, perf will record only
    those events which are present in uprobe_events. This is to make perf
    semantics consistent across normal and SDT events. And If user has
    not used pattern, perf will record all events found from probe-cache
    by reusing name for existing one and adding entries for missing one.
    For ex,

      $ sudo ./perf probe sdt_libpthread:mutex_release
        Added new events:
          sdt_libpthread:mutex_release (on %mutex_release in /usr/lib64/libpthread-2.24.so)
          sdt_libpthread:mutex_release_1 (on %mutex_release in /usr/lib64/libpthread-2.24.so)
          sdt_libpthread:mutex_release_2 (on %mutex_release in /usr/lib64/libpthread-2.24.so)
          sdt_libpthread:mutex_release_3 (on %mutex_release in /usr/lib64/libpthread-2.24.so)
      $ sudo ./perf probe -d sdt_libpthread:mutex_release
      $ sudo ./perf probe -d sdt_libpthread:mutex_release_2

      $ sudo ./perf record -a -e sdt_libpthread:mutex_release*
        Warning: Recording on 2 occurrences of sdt_libpthread:mutex_release*

      $ sudo ./perf record -a -e sdt_libpthread:mutex_release
        Warning: Recording on 4 occurrences of sdt_libpthread:mutex_release

Changes in v5:
  - Patch 2/7 is new. New option introduced in this patch helps to pass
    custome data from builtin-*.c to libperf.

  - All direct callbacks from libelf to builtin-record.c is removed.
 
  - Merged 2nd and 4th patch of v4 into patch 2 of v5.

  - Moved all functions from util/probe-file.c to util/probe-event.c
    which operates on perf_probe_event.

  - Made free_sdt_list() static as it's only used inside util/probe-event.c.

  - Couple of other changes as Masami has suggested in v4 review.

Note: Patchset is prepared on top of acme/perf/core.

v4 link: https://lkml.org/lkml/2017/3/6/565

[1] https://lkml.org/lkml/2017/2/7/59
[2] https://lkml.org/lkml/2016/5/3/810


Hemant Kumar (1):
  perf/sdt: Directly record SDT events with 'perf record'

Ravi Bangoria (6):
  perf/sdt: Introduce util func is_sdt_event()
  perf tool: Add option macro OPT_CALLBACK_ARG
  perf/sdt: Allow recording of existing events
  perf/sdt: Warn when number of events recorded are not equal to cached
    events
  perf/sdt: List events fetched from uprobe_events
  perf/sdt: List events fetched from uprobe_events

 tools/lib/api/fs/tracing_path.c  |  17 +-
 tools/lib/subcmd/parse-options.h |   4 +
 tools/perf/builtin-record.c      |  27 ++-
 tools/perf/util/parse-events.c   |  60 +++++++
 tools/perf/util/parse-events.h   |  23 +++
 tools/perf/util/probe-event.c    | 362 +++++++++++++++++++++++++++++++++++++--
 tools/perf/util/probe-event.h    |  16 ++
 tools/perf/util/probe-file.c     |  48 ++++++
 tools/perf/util/probe-file.h     |   1 +
 9 files changed, 527 insertions(+), 31 deletions(-)

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2.9.3