Date:   Thu, 2 Feb 2023 09:54:42 -0300
From:   Arnaldo Carvalho de Melo <acme@kernel.org>
To:     Namhyung Kim <namhyung@kernel.org>
Cc:     Jiri Olsa <jolsa@kernel.org>, Ingo Molnar <mingo@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Ian Rogers <irogers@google.com>,
        Adrian Hunter <adrian.hunter@intel.com>,
        linux-perf-users@vger.kernel.org, Song Liu <song@kernel.org>,
        Hao Luo <haoluo@google.com>, bpf@vger.kernel.org
Subject: Re: [PATCH 0/4] perf lock contention: Improve aggr x filter
 combination (v1)
Message-ID: <Y9uykljo89Ub5ogb@kernel.org>
References: <20230202050455.2187592-1-namhyung@kernel.org>
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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