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

Namhyung Kim
2024-07-31T17:00:46Z

Hi guys,

On Wed, Jul 31, 2024 at 8:31 AM Liang, Kan <kan.liang@linux.intel.com> wrote:
>
> 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@linux.intel.com wrote:
> >> From: Kan Liang <kan.liang@linux.intel.com>
> >>
> >> 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@linux.intel.com/
> >>
> >> 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!

Sure, I'll take a look!

Thanks,
Namhyung

> >
> >> 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
> >