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

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Date:   Mon, 13 Nov 2023 11:50:16 +0000
From:   Nick Forrington <nick.forrington@....com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>
Cc:     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 08/11/2023 20:28, Arnaldo Carvalho de Melo wrote:
> 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
>   


I'll submit an updated series for this, with the next update to patch 1/2

Thanks,
Nick

>> 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
>>>>>
>>>>>