[PATCH v2 0/4] Tracing contention lock owner call stack

Chun-Tse Shao
2025-01-13T05:22:26Z

For perf lock contention, the current owner tracking (-o option) only
works with per-thread mode (-t option). Enabling call stack mode for
owner can be useful for diagnosing why a system running slow in
lock contention.

Example output:
$ sudo ~/linux/tools/perf/perf lock con -abvo -Y mutex-spin -E16 perf bench sched pipe
...
contended total wait max wait avg wait type caller

171 1.55 ms 20.26 us 9.06 us mutex pipe_read+0x57
0xffffffffac6318e7 pipe_read+0x57
0xffffffffac623862 vfs_read+0x332
0xffffffffac62434b ksys_read+0xbb
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
36 193.71 us 15.27 us 5.38 us mutex pipe_write+0x50
0xffffffffac631ee0 pipe_write+0x50
0xffffffffac6241db vfs_write+0x3bb
0xffffffffac6244ab ksys_write+0xbb
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
4 51.22 us 16.47 us 12.80 us mutex do_epoll_wait+0x24d
0xffffffffac691f0d do_epoll_wait+0x24d
0xffffffffac69249b do_epoll_pwait.part.0+0xb
0xffffffffac693ba5 __x64_sys_epoll_pwait+0x95
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
2 20.88 us 11.95 us 10.44 us mutex do_epoll_wait+0x24d
0xffffffffac691f0d do_epoll_wait+0x24d
0xffffffffac693943 __x64_sys_epoll_wait+0x73
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
1 7.33 us 7.33 us 7.33 us mutex do_epoll_ctl+0x6c1
0xffffffffac692e01 do_epoll_ctl+0x6c1
0xffffffffac6937e0 __x64_sys_epoll_ctl+0x70
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
1 6.64 us 6.64 us 6.64 us mutex do_epoll_ctl+0x3d4
0xffffffffac692b14 do_epoll_ctl+0x3d4
0xffffffffac6937e0 __x64_sys_epoll_ctl+0x70
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76

=== owner stack trace ===

3 31.24 us 15.27 us 10.41 us mutex pipe_read+0x348
0xffffffffac631bd8 pipe_read+0x348
0xffffffffac623862 vfs_read+0x332
0xffffffffac62434b ksys_read+0xbb
0xfffffffface604b2 do_syscall_64+0x82
0xffffffffad00012f entry_SYSCALL_64_after_hwframe+0x76
...

v2: Fix logic deficit in patch 2/4.
Chun-Tse Shao (4):
perf lock: Add bpf maps for owner stack tracing
perf lock: Retrieve owner callstack in bpf program
perf lock: Make rb_tree helper functions generic
perf lock: Report owner stack in usermode

tools/perf/builtin-lock.c | 54 +++--
tools/perf/util/bpf_lock_contention.c | 58 +++++-
.../perf/util/bpf_skel/lock_contention.bpf.c | 192 +++++++++++++++++-
tools/perf/util/bpf_skel/lock_data.h | 6 +
tools/perf/util/lock-contention.h | 2 +
5 files changed, 292 insertions(+), 20 deletions(-)

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2.47.1.688.g23fc6f90ad-goog