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

--
2.9.3

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