linux-kernel - Re: [PATCH 2/2] perf lock info: Enforce exactly one of --map and --thread

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Message-ID: <CAM9d7cjQs0BrFAMa4=PGxxPBoGOAVzermH=0HrA1rhegmAA8zg@mail.gmail.com>
Date:   Wed, 1 Nov 2023 23:00:42 -0700
From:   Namhyung Kim <namhyung@...nel.org>
To:     Nick Forrington <nick.forrington@....com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCH 2/2] perf lock info: Enforce exactly one of --map and --thread

On Wed, Nov 1, 2023 at 7:35 AM Nick Forrington <nick.forrington@....com> wrote:
>
>
> On 31/10/2023 15:38, Arnaldo Carvalho de Melo wrote:
> > Em Tue, Oct 31, 2023 at 12:05:25PM +0000, Nick Forrington escreveu:
> >> Improve error reporting for command line arguments.
> >>
> >> Display error/usage if neither --map or --thread are specified (rather
> >> than a non user-friendly error "Unknown type of information").
> >>
> >> Display error/usage if both --map and --thread are specified (rather
> >> than ignoring "--map" and displaying only thread information).
> > Shouldn't one of them be the default so that we type less for the most
> > common usage?
> >
> > - Arnaldo
> >
>
> There isn't an obvious choice (to me) for which would be the default.
>
> Both options display completely different data/outputs, so I think it
> makes sense to be explicit about which data is requested.

Maybe we can default to display both. :)

Thanks,
Namhyung

>
>
> An alternative could be to use sub-commands e.g. "perf lock info
> threads" or just "perf lock threads", although changing the existing
> options would be more disruptive.
>
>
> Cheers,
> Nick
>
> >> Signed-off-by: Nick Forrington <nick.forrington@....com>
> >> ---
> >>   tools/perf/builtin-lock.c | 25 +++++++++++++++++++++++++
> >>   1 file changed, 25 insertions(+)
> >>
> >> diff --git a/tools/perf/builtin-lock.c b/tools/perf/builtin-lock.c
> >> index 3aa8ba5ad928..cf29f648d291 100644
> >> --- a/tools/perf/builtin-lock.c
> >> +++ b/tools/perf/builtin-lock.c
> >> @@ -2021,6 +2021,27 @@ static int check_lock_report_options(const struct option *options,
> >>      return 0;
> >>   }
> >>
> >> +static int check_lock_info_options(const struct option *options,
> >> +                               const char * const *usage)
> >> +{
> >> +    if (!info_map && !info_threads) {
> >> +            pr_err("Requires one of --map or --threads\n");
> >> +            parse_options_usage(usage, options, "map", 0);
> >> +            parse_options_usage(NULL, options, "threads", 0);
> >> +            return -1;
> >> +
> >> +    }
> >> +
> >> +    if (info_map && info_threads) {
> >> +            pr_err("Cannot show map and threads together\n");
> >> +            parse_options_usage(usage, options, "map", 0);
> >> +            parse_options_usage(NULL, options, "threads", 0);
> >> +            return -1;
> >> +    }
> >> +
> >> +    return 0;
> >> +}
> >> +
> >>   static int check_lock_contention_options(const struct option *options,
> >>                                       const char * const *usage)
> >>
> >> @@ -2709,6 +2730,10 @@ int cmd_lock(int argc, const char **argv)
> >>                      if (argc)
> >>                              usage_with_options(info_usage, info_options);
> >>              }
> >> +
> >> +            if (check_lock_info_options(info_options, info_usage) < 0)
> >> +                    return -1;
> >> +
> >>              /* recycling report_lock_ops */
> >>              trace_handler = &report_lock_ops;
> >>              rc = __cmd_report(true);
> >> --
> >> 2.42.0
> >>
> >>