Re: [PATCH 0/9] Support branch counters in block annotation

From: Liang, Kan
Date: Wed Jul 31 2024 - 11:33:52 EST

Hi Arnaldo,

On 2024-07-31 11:05 a.m., Arnaldo Carvalho de Melo wrote:
> On Wed, Jul 03, 2024 at 01:03:47PM -0700, kan.liang@xxxxxxxxxxxxxxx wrote:
>> From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
>>
>> The branch counters logging (A.K.A LBR event logging) introduces a
>> per-counter indication of precise event occurrences in LBRs. It can
>> provide a means to attribute exposed retirement latency to combinations
>> of events across a block of instructions. It also provides a means of
>> attributing Timed LBR latencies to events.
>>
>> The kernel support and basic perf tool support have been merged.
>> https://lore.kernel.org/lkml/20231025201626.3000228-1-kan.liang@xxxxxxxxxxxxxxx/
>>
>> This series is to provide advanced perf tool support via adding the
>> branch counters information in block annotation. It can further
>> facilitate the analysis of branch blocks.
>>
>> The patch 1 and 2 are to fix two existing issues of --total-cycles and
>> the branch counters feature.
>>
>> The patch 3-9 are the advanced perf tool support.
>
> I couldn't find any newer versions of this series nor reviews, is that
> right?

Right. There is no newer version nor reviews.

The patch series can be successfully applied on top of the latest
tmp.perf-tools-next (on top of the commit 756785ab6380 ("perf list: Give
clues if failed to open tracing events directory")).

I think we can still use it for the review.

>
> I'll try and review this soon, but if someone else could take a look,
> try it and provide a Reviewed-by or at least an Acked-by, that would
> help!

Thanks!

Kan
>
> - Arnaldo
>
>> Here are some examples.
>>
>> perf annotation:
>>
>> $perf record -e "{branch-instructions:ppp,branch-misses}:S" -j any,counter
>> $perf report --total-cycles --stdio
>>
>> # To display the perf.data header info, please use --header/--header-only options.
>> #
>> #
>> # Total Lost Samples: 0
>> #
>> # Samples: 1M of events 'anon group { branch-instructions:ppp, branch-misses }'
>> # Event count (approx.): 1610046
>> #
>> # Branch counter abbr list:
>> # branch-instructions:ppp = A
>> # branch-misses = B
>> # '-' No event occurs
>> # '+' Event occurrences may be lost due to branch counter saturated
>> #
>> # Sampled Cycles% Sampled Cycles Avg Cycles% Avg Cycles Branch Counter [Program Block Range]
>> # ............... .............. ........... .......... ...................... ..
>> #
>> 57.55% 2.5M 0.00% 3 |A |- | ...
>> 25.27% 1.1M 0.00% 2 |AA |- | ...
>> 15.61% 667.2K 0.00% 1 |A |- | ...
>> 0.16% 6.9K 0.81% 575 |A |- | ...
>> 0.16% 6.8K 1.38% 977 |AA |- | ...
>> 0.16% 6.8K 0.04% 28 |AA |B | ...
>> 0.15% 6.6K 1.33% 946 |A |- | ...
>> 0.11% 4.5K 0.06% 46 |AAA+|- | ...
>>
>> (The below output is in the TUI mode. Users can press 'B' to display
>> the Branch counter abbr list.)
>>
>> Samples: 1M of events 'anon group { branch-instructions:ppp, branch-misses }',
>> 4000 Hz, Event count (approx.):
>> f3 /home/sdp/test/tchain_edit [Percent: local period]
>> Percent │ IPC Cycle Branch Counter (Average IPC: 1.39, IPC Coverage: 29.4%)
>> │ 0000000000401755 <f3>:
>> 0.00 0.00 │ endbr64
>> │ push %rbp
>> │ mov %rsp,%rbp
>> │ movl $0x0,-0x4(%rbp)
>> 0.00 0.00 │1.33 3 |A |- | ↓ jmp 25
>> 11.03 11.03 │ 11: mov -0x4(%rbp),%eax
>> │ and $0x1,%eax
>> │ test %eax,%eax
>> 17.13 17.13 │2.41 1 |A |- | ↓ je 21
>> │ addl $0x1,-0x4(%rbp)
>> 21.84 21.84 │2.22 2 |AA |- | ↓ jmp 25
>> 17.13 17.13 │ 21: addl $0x1,-0x4(%rbp)
>> 21.84 21.84 │ 25: cmpl $0x270f,-0x4(%rbp)
>> 11.03 11.03 │0.61 3 |A |- | ↑ jle 11
>> │ nop
>> │ pop %rbp
>> 0.00 0.00 │0.24 20 |AA |B | ← ret
>>
>> perf script:
>>
>> $perf script -F +brstackinsn,+brcntr
>>
>> # Branch counter abbr list:
>> # branch-instructions:ppp = A
>> # branch-misses = B
>> # '-' No event occurs
>> # '+' Event occurrences may be lost due to branch counter saturated
>> tchain_edit 332203 3366329.405674: 53030 branch-instructions:ppp: 401781 f3+0x2c (home/sdp/test/tchain_edit)
>> f3+31:
>> 0000000000401774 insn: eb 04 br_cntr: AA # PRED 5 cycles [5]
>> 000000000040177a insn: 81 7d fc 0f 27 00 00
>> 0000000000401781 insn: 7e e3 br_cntr: A # PRED 1 cycles [6] 2.00 IPC
>> 0000000000401766 insn: 8b 45 fc
>> 0000000000401769 insn: 83 e0 01
>> 000000000040176c insn: 85 c0
>>
>> $perf script -F +brstackinsn,+brcntr -v
>>
>> tchain_edit 332203 3366329.405674: 53030 branch-instructions:ppp: 401781 f3+0x2c (/home/sdp/test/tchain_edit)
>> f3+31:
>> 0000000000401774 insn: eb 04 br_cntr: branch-instructions:ppp 2 branch-misses 0 # PRED 5 cycles [5]
>> 000000000040177a insn: 81 7d fc 0f 27 00 00
>> 0000000000401781 insn: 7e e3 br_cntr: branch-instructions:ppp 1 branch-misses 0 # PRED 1 cycles [6] 2.00 IPC
>> 0000000000401766 insn: 8b 45 fc
>> 0000000000401769 insn: 83 e0 01
>> 000000000040176c insn: 85 c0
>>
>> Kan Liang (9):
>> perf report: Fix --total-cycles --stdio output error
>> perf report: Remove the first overflow check for branch counters
>> perf evlist: Save branch counters information
>> perf annotate: Save branch counters for each block
>> perf evsel: Assign abbr name for the branch counter events
>> perf report: Display the branch counter histogram
>> perf annotate: Display the branch counter histogram
>> perf script: Add branch counters
>> perf test: Add new test cases for the branch counter feature
>>
>> tools/perf/Documentation/perf-report.txt | 1 +
>> tools/perf/Documentation/perf-script.txt | 2 +-
>> tools/perf/builtin-annotate.c | 13 +-
>> tools/perf/builtin-diff.c | 8 +-
>> tools/perf/builtin-report.c | 25 ++-
>> tools/perf/builtin-script.c | 69 +++++++-
>> tools/perf/builtin-top.c | 4 +-
>> tools/perf/tests/shell/record.sh | 17 +-
>> tools/perf/ui/browsers/annotate.c | 18 +-
>> tools/perf/ui/browsers/hists.c | 18 +-
>> tools/perf/util/annotate.c | 209 +++++++++++++++++++++--
>> tools/perf/util/annotate.h | 24 ++-
>> tools/perf/util/block-info.c | 66 ++++++-
>> tools/perf/util/block-info.h | 8 +-
>> tools/perf/util/branch.h | 1 +
>> tools/perf/util/disasm.c | 1 +
>> tools/perf/util/evlist.c | 66 +++++++
>> tools/perf/util/evlist.h | 2 +
>> tools/perf/util/evsel.c | 15 +-
>> tools/perf/util/evsel.h | 12 ++
>> tools/perf/util/hist.c | 5 +-
>> tools/perf/util/hist.h | 2 +-
>> tools/perf/util/machine.c | 3 +
>> 23 files changed, 519 insertions(+), 70 deletions(-)
>>
>> --
>> 2.38.1
>