linux-kernel - Re: [PATCHSET 0/7] perf lock: New lock contention tracepoints support (v4)

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Message-ID: <CAM9d7cjD=at=AtKmvMLogjN6mieWVR2kk-HigxO01cvPPRGFBg@mail.gmail.com>
Date:   Fri, 24 Jun 2022 09:40:05 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...nel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ian Rogers <irogers@...gle.com>,
        linux-perf-users <linux-perf-users@...r.kernel.org>,
        Will Deacon <will@...nel.org>,
        Waiman Long <longman@...hat.com>,
        Boqun Feng <boqun.feng@...il.com>,
        Davidlohr Bueso <dave@...olabs.net>
Subject: Re: [PATCHSET 0/7] perf lock: New lock contention tracepoints support (v4)

Ping!  Any comments?


On Wed, Jun 15, 2022 at 9:32 AM Namhyung Kim <namhyung@...nel.org> wrote:
>
> Hello,
>
> Kernel v5.19 will have a new set of tracepoints to track lock
> contentions for various lock types.  Unlike tracepoints in LOCKDEP and
> LOCK_STAT, it's hit only for contended locks and lock names are not
> available.  So it needs to collect stack traces and display the caller
> function instead.
>
> Changes in v4)
>  * add Acked-by from Ian
>  * more comments on trace_lock_handler
>  * don't create stats in the contention_end handler
>
> Changes in v3)
>  * fix build error
>  * support data from different kernels/machines
>  * skip bad stat unless there's actual bad ones
>
> Changes in v2)
>  * add Acked-by from Ian
>  * print time with a unit for compact output
>  * add some comments  (Ian)
>  * remove already applied patch
>
> This patchset merely adds support for the new tracepoints to the
> existing perf lock commands.  So there's no change to the user.  Later
> I'll add new a sub-command dedicated to the tracepoints to make use of
> the additional information.
>
> Example output:
>
>   $ sudo perf lock record -a sleep 3
>
>   $ perf lock report -F acquired,contended,avg_wait,wait_total
>
>                   Name   acquired  contended     avg wait    total wait
>
>    update_blocked_a...         40         40      3.61 us     144.45 us
>    kernfs_fop_open+...          5          5      3.64 us      18.18 us
>     _nohz_idle_balance          3          3      2.65 us       7.95 us
>    tick_do_update_j...          1          1      6.04 us       6.04 us
>     ep_scan_ready_list          1          1      3.93 us       3.93 us
>   ...
>
> You can find the code in the 'perf/lock-contention-v4' branch at
>
>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
>
> Thanks,
> Namhyung
>
>
> Namhyung Kim (7):
>   perf lock: Print wait times with unit
>   perf lock: Allow to use different kernel symbols
>   perf lock: Skip print_bad_events() if nothing bad
>   perf lock: Add lock contention tracepoints record support
>   perf lock: Handle lock contention tracepoints
>   perf record: Allow to specify max stack depth of fp callchain
>   perf lock: Look up callchain for the contended locks
>
>  tools/perf/Documentation/perf-lock.txt   |   7 +
>  tools/perf/Documentation/perf-record.txt |   5 +
>  tools/perf/builtin-lock.c                | 426 ++++++++++++++++++++++-
>  tools/perf/util/callchain.c              |  18 +-
>  4 files changed, 434 insertions(+), 22 deletions(-)
>
>
> base-commit: 9886142c7a2226439c1e3f7d9b69f9c7094c3ef6
> --
> 2.36.1.476.g0c4daa206d-goog
>