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

[Namhyung Kim]

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