linux-kernel - [RFC/PATCH 0/3] perf lock contention: Track lock owner (v2)

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Message-Id: <20230207002403.63590-1-namhyung@kernel.org>
Date:   Mon,  6 Feb 2023 16:24:00 -0800
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>,
        Adrian Hunter <adrian.hunter@...el.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>,
        Song Liu <song@...nel.org>, Hao Luo <haoluo@...gle.com>,
        bpf@...r.kernel.org
Subject: [RFC/PATCH 0/3] perf lock contention: Track lock owner (v2)

Hello,

When there're many lock contentions in the system, people sometimes
want to know who caused the contention, IOW who's the owner of the
locks.

This patchset adds -o/--lock-owner option to track the owner info
if it's available.  Right now, it supports mutex and rwsem as they
have the owner fields in themselves.  Please see the patch 2 for the
details.

Changes in v2)
 * fix missing callstacks
 * support old rwsem type with recent clang (>= 15.0)

The patch 1 is a fix for missing callstacks and the patch 2 is the
main change.  The patch 3 adds support for old kernels when compiler
supports a recent builtin to check field type in a struct (Thanks
to Hao).

Example output (for mutex only):

  $ sudo ./perf lock con -abo -Y mutex -- ./perf bench sched pipe
  # Running 'sched/pipe' benchmark:
  # Executed 1000000 pipe operations between two processes

       Total time: 4.910 [sec]

         4.910435 usecs/op
           203647 ops/sec
   contended   total wait     max wait     avg wait          pid   owner

           2     15.50 us      8.29 us      7.75 us      1582852   sched-pipe
           7      7.20 us      2.47 us      1.03 us           -1   Unknown
           1      6.74 us      6.74 us      6.74 us      1582851   sched-pipe

You can get it from 'perf/lock-owner-v2' branch in

  git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git

Thanks,
Namhyung

Namhyung Kim (3):
  perf lock contention: Fix to save callstack for the default modified
  perf lock contention: Add -o/--lock-owner option
  perf lock contention: Support old rw_semaphore type

 tools/perf/Documentation/perf-lock.txt        |  5 +
 tools/perf/builtin-lock.c                     | 52 +++++++++--
 tools/perf/util/bpf_lock_contention.c         |  1 +
 .../perf/util/bpf_skel/lock_contention.bpf.c  | 91 ++++++++++++++++++-
 tools/perf/util/lock-contention.h             |  1 +
 5 files changed, 136 insertions(+), 14 deletions(-)


base-commit: 17f248aa8664ff5b3643491136283e73b5c18166
-- 
2.39.1.519.gcb327c4b5f-goog