Re: [PATCH 2/3] perf lock contention: Add -o/--lock-owner option

[Namhyung Kim]

Hi Arnaldo,

On Tue, Feb 7, 2023 at 7:11 AM Arnaldo Carvalho de Melo <acme@xxxxxxxxxx> wrote:
>
> Em Mon, Feb 06, 2023 at 04:24:02PM -0800, Namhyung Kim escreveu:
> > 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.
> >
> > The -o/--lock-owner option tries to follow the lock owners for the
> > contended mutexes and rwsems from BPF, and then attributes the
> > contention time to the owner instead of the waiter.  It's a best
> > effort approach to get the owner info at the time of the contention
> > and doesn't guarantee to have the precise tracking of owners if it's
> > changing over time.
>
> Having this in the documentation as limitations of the approach helps,
> but I'm not seeing this on this specific patch, where I think it should
> be.
>
> Furthermore probably its a good idea to have this as a warning on the
> actual output of the tool, no?
>
> Generally having cool commit log messages, as this one has, is great,
> but people have difficulty looking at docs, imagine expecting them to
> read commit log messages... :-)

I see.  I'll add this limitation to the doc and tool output.

Thanks,
Namhyung