linux-kernel - Re: [PATCHSET 0/5] perf lock: Add contention subcommand (v2)

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Date:   Mon, 25 Jul 2022 18:01:32 -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@...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 0/5] perf lock: Add contention subcommand (v2)

Em Mon, Jul 25, 2022 at 11:31:19AM -0700, Namhyung Kim escreveu:
> Hello,
> 
> It's to add a new subcommand 'contention' (shortly 'con') to perf lock.
> 
> Changes in v2)
> * bugfix is merged already
> * fix build error in patch 2
> 
> The new subcommand is to handle the new lock:contention_{begin,end}
> tracepoints and shows lock type and caller address like below:
> 
>   $ perf lock contention
>    contended   total wait     max wait     avg wait         type   caller
> 
>          238      1.41 ms     29.20 us      5.94 us     spinlock   update_blocked_averages+0x4c
>            1    902.08 us    902.08 us    902.08 us      rwsem:R   do_user_addr_fault+0x1dd
>           81    330.30 us     17.24 us      4.08 us     spinlock   _nohz_idle_balance+0x172
>            2     89.54 us     61.26 us     44.77 us     spinlock   do_anonymous_page+0x16d
>           24     78.36 us     12.27 us      3.27 us        mutex   pipe_read+0x56
>            2     71.58 us     59.56 us     35.79 us     spinlock   __handle_mm_fault+0x6aa
>            6     25.68 us      6.89 us      4.28 us     spinlock   do_idle+0x28d
>            1     18.46 us     18.46 us     18.46 us      rtmutex   exec_fw_cmd+0x21b
>            3     15.25 us      6.26 us      5.08 us     spinlock   tick_do_update_jiffies64+0x2c
>    ...
> 
> where rwsem:R stands for read access (down_read) for a rw-semaphore.
> Other types of lock access is obvious and it doesn't detect optimistic
> spinning on mutex yet.  This is just a base work for lock contention
> analysis and more will come later.
> 
> You can get this from 'perf/lock-subcmd-v2' branch on
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git

Thanks, applied locally, pushed to tmp.perf/core, will go to perf/core
after further automated tests.

- Arnaldo
 
> Thanks,
> Namhyung
> 
> 
> Namhyung Kim (5):
>   perf lock: Add flags field in the lock_stat
>   perf lock: Add lock aggregation enum
>   perf lock: Add 'contention' subcommand
>   perf lock: Add -k and -F options to 'contention' subcommand
>   perf lock: Support -t option for 'contention' subcommand
> 
>  tools/perf/Documentation/perf-lock.txt |  23 +-
>  tools/perf/builtin-lock.c              | 401 +++++++++++++++++++++++--
>  2 files changed, 390 insertions(+), 34 deletions(-)
> 
> 
> base-commit: 9fe9b252c7c022df8e503435e778f15c04dfa3bf
> -- 
> 2.37.1.359.gd136c6c3e2-goog

-- 

- Arnaldo