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

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Message-ID: <YrYJq8UQ04FFN12/@kernel.org>
Date:   Fri, 24 Jun 2022 15:59:55 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Jiri Olsa <jolsa@...nel.org>, 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)

Em Fri, Jun 24, 2022 at 09:40:05AM -0700, Namhyung Kim escreveu:
>> Ping!  Any comments?

 
I'll take a look and test it soon.

- Arnaldo

> 
> 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
> >

-- 

- Arnaldo