[RFCv2 0/9] perf: Allow leader sampling on inherited events

From: Jiri Olsa
Date: Mon Aug 25 2014 - 10:46:30 EST

Jen-Cheng(Tommy) Huang reported the leader sampling not working
on children processes:

The leader sampling (example below) lets the group leader event (cycles)
do the sampling and reads the rest of the group (cache-misses) via

$ perf record -e '{cycles,cache-misses}:S' <workload>
$ perf report --group

The perf report --group allows to see all events group
data in single view.

The reason for leader sampling being switched off for inherited
events, is that the kernel does no allow PERF_FORMAT_GROUP format
on inherited events (which is used by leader sampling).

I switched on the PERF_FORMAT_GROUP format for inherited events
with few other fixies in patches:
perf: Deny optimized switch for events read by PERF_SAMPLE_READ
perf: Allow PERF_FORMAT_GROUP format on inherited events

And I fixed perf tool code to be able to process data from
children processes.

Anyway, I might have missed some other reason why this was
never switched on in kernel, so sending this as RFC.

v2 changes:
- detection of the kernel support
- added perf script support for period column
- separate kernel change for context_equiv change

thanks for comments,

Reported-by: Jen-Cheng(Tommy) Huang <tommy24@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Cc: Corey Ashford <cjashfor@xxxxxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jen-Cheng(Tommy) Huang <tommy24@xxxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Stephane Eranian <eranian@xxxxxxxxxx>
Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Jiri Olsa (9):
perf: Remove redundant parent context check from context_equiv
perf: Deny optimized switch for events read by PERF_SAMPLE_READ
perf: Allow PERF_FORMAT_GROUP format on inherited events
perf tools: Add support to traverse xyarrays
perf tools: Add pr_warning_once debug macro
perf tools: Add hash of periods for struct perf_sample_id
perf tools: Allow PERF_FORMAT_GROUP for inherited events
perf script: Add period data column
perf script: Add period as a default output column

kernel/events/core.c | 33 ++++++++++++++------------------
tools/perf/Documentation/perf-script.txt | 2 +-
tools/perf/Makefile.perf | 1 +
tools/perf/builtin-script.c | 21 +++++++++++++++++----
tools/perf/perf.h | 1 +
tools/perf/tests/builtin-test.c | 4 ++++
tools/perf/tests/tests.h | 1 +
tools/perf/tests/xyarray.c | 33 ++++++++++++++++++++++++++++++++
tools/perf/util/debug.h | 12 ++++++++++++
tools/perf/util/evsel.c | 19 ++++++++++++++++++-
tools/perf/util/evsel.h | 5 ++++-
tools/perf/util/record.c | 12 ++++++++++++
tools/perf/util/session.c | 93 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
tools/perf/util/xyarray.c | 4 +++-
tools/perf/util/xyarray.h | 6 ++++++
15 files changed, 214 insertions(+), 33 deletions(-)
create mode 100644 tools/perf/tests/xyarray.c
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