linux-kernel - Re: [PATCH 3/5] perf record: Add new option to sample identifier

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Message-ID: <CAP-5=fVWOeqZ+BePoe3Te1fCaru_O5u+E0Lah8pGvSOfLDQaWQ@mail.gmail.com>
Date:   Tue, 14 Jun 2022 07:53:01 -0700
From:   Ian Rogers <irogers@...gle.com>
To:     Adrian Hunter <adrian.hunter@...el.com>
Cc:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/5] perf record: Add new option to sample identifier

On Fri, Jun 10, 2022 at 4:33 AM Adrian Hunter <adrian.hunter@...el.com> wrote:
>
> In preparation for recording sideband events in a virtual machine guest so
> that they can be injected into a host perf.data file.
>
> Add an option to always include sample type PERF_SAMPLE_IDENTIFIER.
>
> Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
> ---
>  tools/perf/Documentation/perf-record.txt | 3 +++
>  tools/perf/builtin-record.c              | 2 ++
>  tools/perf/util/record.c                 | 2 +-
>  tools/perf/util/record.h                 | 1 +
>  4 files changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
> index cf8ad50f3de1..8fcea74fe3c2 100644
> --- a/tools/perf/Documentation/perf-record.txt
> +++ b/tools/perf/Documentation/perf-record.txt
> @@ -313,6 +313,9 @@ OPTIONS
>  --sample-cpu::
>         Record the sample cpu.
>
> +--sample-identifier::
> +       Record the sample identifier.

I can see this is following the pattern of --sample-cpu above, but I'm
not sure a "sample identifier" is going to be clear to a novice user.
The comment adds little beyond the option name. Perhaps expand with an
example?

Thanks,
Ian

> +
>  -n::
>  --no-samples::
>         Don't sample.
> diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
> index 00c2a6cdf1be..40dca1fba4e3 100644
> --- a/tools/perf/builtin-record.c
> +++ b/tools/perf/builtin-record.c
> @@ -3191,6 +3191,8 @@ static struct option __record_options[] = {
>         OPT_BOOLEAN(0, "code-page-size", &record.opts.sample_code_page_size,
>                     "Record the sampled code address (ip) page size"),
>         OPT_BOOLEAN(0, "sample-cpu", &record.opts.sample_cpu, "Record the sample cpu"),
> +       OPT_BOOLEAN(0, "sample-identifier", &record.opts.sample_identifier,
> +                   "Record the sample identifier"),
>         OPT_BOOLEAN_SET('T', "timestamp", &record.opts.sample_time,
>                         &record.opts.sample_time_set,
>                         "Record the sample timestamps"),
> diff --git a/tools/perf/util/record.c b/tools/perf/util/record.c
> index 5b09ecbb05dc..b529636ab3ea 100644
> --- a/tools/perf/util/record.c
> +++ b/tools/perf/util/record.c
> @@ -121,7 +121,7 @@ void evlist__config(struct evlist *evlist, struct record_opts *opts, struct call
>         evlist__for_each_entry(evlist, evsel)
>                 evsel__config_leader_sampling(evsel, evlist);
>
> -       if (opts->full_auxtrace) {
> +       if (opts->full_auxtrace || opts->sample_identifier) {
>                 /*
>                  * Need to be able to synthesize and parse selected events with
>                  * arbitrary sample types, which requires always being able to
> diff --git a/tools/perf/util/record.h b/tools/perf/util/record.h
> index be9a957501f4..4269e916f450 100644
> --- a/tools/perf/util/record.h
> +++ b/tools/perf/util/record.h
> @@ -28,6 +28,7 @@ struct record_opts {
>         bool          sample_time;
>         bool          sample_time_set;
>         bool          sample_cpu;
> +       bool          sample_identifier;
>         bool          period;
>         bool          period_set;
>         bool          running_time;
> --
> 2.25.1
>