Re: [PATCH 0/9] Support branch counters in block annotation
From: Arnaldo Carvalho de Melo
Date: Wed Jul 31 2024 - 11:05:40 EST
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?
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!
- 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