[PATCH v1 0/5] perf report: Show branch type

Jin Yao
2017-03-31T07:20:41Z

It is often useful to know the branch types while analyzing branch
data. For example, a call is very different from a conditional branch.

Currently we have to look it up in binary while the binary may later
not be available and even the binary is available but user has to take
some time. It is very useful for user to check it directly in perf
report.

Perf already has support for disassembling the branch instruction
to get the branch type.

The patch series records the branch type and show the branch type with
other LBR information in callchain entry via perf report. The patch
series also adds the branch type summary at the end of
perf report --stdio.

To keep consistent on kernel and userspace and make the classification
more common, the patch adds the common branch type classification
in perf_event.h.

The common branch types are:

JCC forward: Conditional forward jump
JCC backward: Conditional backward jump
JMP: Jump imm
IND_JMP: Jump reg/mem
CALL: Call imm
IND_CALL: Call reg/mem
RET: Ret
FAR_BRANCH: SYSCALL/SYSRET, IRQ, IRET, TSX Abort

An example:

1. Record branch type (new option "save_type")

perf record -g --branch-filter any,save_type <command>

2. Show the branch type statistics at the end of perf report --stdio

perf report --stdio

JCC forward: 34.0%
JCC backward: 3.6%
JMP: 0.0%
IND_JMP: 6.5%
CALL: 26.6%
IND_CALL: 0.0%
RET: 29.3%
FAR_BRANCH: 0.0%

3. Show branch type in callchain entry

perf report --branch-history --stdio --no-children

--23.91%--main div.c:42 (RET cycles:2)
compute_flag div.c:28 (RET cycles:2)
compute_flag div.c:27 (RET cycles:1)
rand rand.c:28 (RET cycles:1)
rand rand.c:28 (RET cycles:1)
__random random.c:298 (RET cycles:1)
__random random.c:297 (JCC forward cycles:1)
__random random.c:295 (JCC forward cycles:1)
__random random.c:295 (JCC forward cycles:1)
__random random.c:295 (JCC forward cycles:1)
__random random.c:295 (RET cycles:9)

Jin Yao (5):
perf/core: Define the common branch type classification
perf/x86/intel: Record branch type
perf record: Create a new option save_type in --branch-filter
perf report: Show branch type statistics for stdio mode
perf report: Show branch type in callchain entry

arch/x86/events/intel/lbr.c | 69 ++++++++++++-
include/uapi/linux/perf_event.h | 24 ++++-
tools/include/uapi/linux/perf_event.h | 24 ++++-
tools/perf/Documentation/perf-record.txt | 1 +
tools/perf/builtin-report.c | 140 ++++++++++++++++++++++++++
tools/perf/util/callchain.c | 168 ++++++++++++++++++++-----------
tools/perf/util/callchain.h | 13 +++
tools/perf/util/event.h | 3 +-
tools/perf/util/hist.c | 5 +-
tools/perf/util/parse-branch-options.c | 1 +
10 files changed, 381 insertions(+), 67 deletions(-)

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2.7.4