hi,
Jen-Cheng(Tommy) Huang reported the leader sampling not working
on children processes:
http://www.mail-archive.com/[email protected]/msg01644.html
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_FORMAT_GROUP format.
Example:
$ 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.
thanks for comments,
jirka
Reported-by: Jen-Cheng(Tommy) Huang <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Arnaldo Carvalho de Melo <[email protected]>
Cc: Corey Ashford <[email protected]>
Cc: David Ahern <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jen-Cheng(Tommy) Huang <[email protected]>
Cc: Namhyung Kim <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Signed-off-by: Jiri Olsa <[email protected]>
---
Jiri Olsa (5):
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 hash of periods for struct perf_sample_id
perf tools: Allow PERF_FORMAT_GROUP for inherited events
kernel/events/core.c | 25 ++++++++++++++-----------
tools/perf/Makefile.perf | 1 +
tools/perf/tests/builtin-test.c | 4 ++++
tools/perf/tests/tests.h | 1 +
tools/perf/tests/xyarray.c | 33 +++++++++++++++++++++++++++++++++
tools/perf/util/evsel.c | 17 ++++++++++++++---
tools/perf/util/evsel.h | 5 ++++-
tools/perf/util/session.c | 93
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++------
tools/perf/util/xyarray.c | 4 +++-
tools/perf/util/xyarray.h | 6 ++++++
10 files changed, 167 insertions(+), 22 deletions(-)
create mode 100644 tools/perf/tests/xyarray.c
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