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

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Date:   Wed, 8 Nov 2023 17:28:14 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Namhyung Kim <namhyung@...nel.org>
Cc:     Nick Forrington <nick.forrington@....com>,
        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

Em Wed, Nov 01, 2023 at 11:00:42PM -0700, Namhyung Kim escreveu:
> 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. :)

Yeah, that would be a better approach, I think.

- Arnaldo
 
> 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
> > >>
> > >>

-- 

- Arnaldo