Re: [PATCH 0/4] perf lock contention: Improve aggr x filter combination (v1)

Arnaldo Carvalho de Melo
2023-02-02T12:55:07Z

Em Wed, Feb 01, 2023 at 09:04:51PM -0800, Namhyung Kim escreveu:
> Hello,
>
> The callstack filter can be useful to debug lock issues but it has a
> limitation that it only works with caller aggregation mode (which is the
> default setting). IOW it cannot filter by callstack when showing tasks
> or lock addresses/names.

Thanks, applied, the only nit was for a preexisting problem I only
caught now in a refactoring, please consider fixing those.

- Arnaldo

> But sometimes users want to use the filter for other aggregation mode.
> Like "show me lock addresses/names from this caller only" or "show me
> tasks having these callers".
>
> When it's using tracepoint events from the data file, the situation is
> good since the tracepoints have all the necessary info. But when using
> BPF it needs to extend the key of lock stat BPF map to have more than
> one info like 'pid + stack_id' or 'lock_addr + stack_id'. As callstack
> filter works in userspace, it should save the both info.
>
> With this change we can now use the -S/--callstack-filter with the
> -t/--threads option or -l/--lock-addr option. It's also possible to use
> it with other filter options.
>
> The following example shows the top 5 tasks that have contention
> somewhere in the epoll handling.
>
> $ sudo perf lock con -abt -S epoll -E5 -- sleep 1
> contended total wait max wait avg wait pid comm
>
> 2 58.64 us 32.38 us 29.32 us 1514752 Chrome_IOThread
> 3 29.31 us 12.65 us 9.77 us 3773 Xorg
> 1 17.45 us 17.45 us 17.45 us 1514906 Chrome_ChildIOT
> 1 15.41 us 15.41 us 15.41 us 1515382 Chrome_ChildIOT
> 1 12.52 us 12.52 us 12.52 us 293878 IPC I/O Parent
>
> You get get the code at 'perf/lock-filter-v1' branch in
>
> git://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git
>
> Thanks,
> Namhyung
>
> Namhyung Kim (4):
> perf lock contention: Factor out lock_contention_get_name()
> perf lock contention: Use lock_stat_find{,new}
> perf lock contention: Support filters for different aggregation
> perf test: Add more test cases for perf lock contention
>
> tools/perf/builtin-lock.c | 79 ++++----
> tools/perf/tests/shell/lock_contention.sh | 66 ++++++-
> tools/perf/util/bpf_lock_contention.c | 178 +++++++++++-------
> .../perf/util/bpf_skel/lock_contention.bpf.c | 15 +-
> tools/perf/util/bpf_skel/lock_data.h | 4 +-
> tools/perf/util/lock-contention.h | 5 +
> 6 files changed, 234 insertions(+), 113 deletions(-)
>
>
> base-commit: 7cfa9f5e440054db7c7e28e83a045d36993ff958
> --
> 2.39.1.456.gfc5497dd1b-goog
>

--

- Arnaldo