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Message-ID: <CAP-5=fWOji8vCQfO-y4HnmFk2k+F70BtGHTjCg6XyORNfYNcww@mail.gmail.com>
Date: Wed, 21 Jun 2023 00:05:34 -0700
From: Ian Rogers <irogers@...gle.com>
To: Namhyung Kim <namhyung@...nel.org>
Cc: Arnaldo Carvalho de Melo <acme@...nel.org>,
Jiri Olsa <jolsa@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Peter Zijlstra <peterz@...radead.org>,
Ingo Molnar <mingo@...nel.org>,
LKML <linux-kernel@...r.kernel.org>,
linux-perf-users@...r.kernel.org
Subject: Re: [PATCH] tools lib subcmd: Show parent options in help
On Thu, May 25, 2023 at 3:09 PM Namhyung Kim <namhyung@...nel.org> wrote:
>
> I've just realized that help message in a subcommand didn't show one
> in the parent command. Since the option parser understands the parent,
> display code should do the same. For example, `perf ftrace latency -h`
> should show options in the `perf ftrace` command too.
>
> Before:
>
> $ perf ftrace latency -h
>
> Usage: perf ftrace [<options>] [<command>]
> or: perf ftrace [<options>] -- [<command>] [<options>]
> or: perf ftrace {trace|latency} [<options>] [<command>]
> or: perf ftrace {trace|latency} [<options>] -- [<command>] [<options>]
>
> -b, --use-bpf Use BPF to measure function latency
> -n, --use-nsec Use nano-second histogram
> -T, --trace-funcs <func>
> Show latency of given function
>
> After:
>
> $ perf ftrace latency -h
>
> Usage: perf ftrace [<options>] [<command>]
> or: perf ftrace [<options>] -- [<command>] [<options>]
> or: perf ftrace {trace|latency} [<options>] [<command>]
> or: perf ftrace {trace|latency} [<options>] -- [<command>] [<options>]
>
> -a, --all-cpus System-wide collection from all CPUs
> -b, --use-bpf Use BPF to measure function latency
> -C, --cpu <cpu> List of cpus to monitor
> -n, --use-nsec Use nano-second histogram
> -p, --pid <pid> Trace on existing process id
> -T, --trace-funcs <func>
> Show latency of given function
> -v, --verbose Be more verbose
> --tid <tid> Trace on existing thread id (exclusive to --pid)
>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
> tools/lib/subcmd/parse-options.c | 26 ++++++++++++++++++--------
> 1 file changed, 18 insertions(+), 8 deletions(-)
>
> diff --git a/tools/lib/subcmd/parse-options.c b/tools/lib/subcmd/parse-options.c
> index 9fa75943f2ed..41de97671c72 100644
> --- a/tools/lib/subcmd/parse-options.c
> +++ b/tools/lib/subcmd/parse-options.c
> @@ -806,18 +806,28 @@ static int option__cmp(const void *va, const void *vb)
>
> static struct option *options__order(const struct option *opts)
> {
> - int nr_opts = 0, nr_group = 0, len;
> - const struct option *o = opts;
> - struct option *opt, *ordered, *group;
> + int nr_opts = 0, nr_group = 0, nr_parent = 0, len;
> + const struct option *o, *p = opts;
> + struct option *opt, *ordered = NULL, *group;
>
> - for (o = opts; o->type != OPTION_END; o++)
> +retry:
Why use "goto retry" and not compute the size with the parent upfront?
> + for (o = p; o->type != OPTION_END; o++)
> ++nr_opts;
>
> - len = sizeof(*o) * (nr_opts + 1);
> - ordered = malloc(len);
> - if (!ordered)
> + len = sizeof(*o) * (nr_opts + !o->parent);
It'd be nice to comment on why the "!o->parent" here.
Thanks,
Ian
> + group = realloc(ordered, len);
> + if (!group)
> goto out;
> - memcpy(ordered, opts, len);
> + ordered = group;
> + memcpy(&ordered[nr_parent], p, sizeof(*o) * (nr_opts - nr_parent));
> +
> + if (o->parent) {
> + p = o->parent;
> + nr_parent = nr_opts;
> + goto retry;
> + }
> + /* copy the last OPTION_END */
> + memcpy(&ordered[nr_opts], o, sizeof(*o));
>
> /* sort each option group individually */
> for (opt = group = ordered; opt->type != OPTION_END; opt++) {
> --
> 2.41.0.rc0.172.g3f132b7071-goog
>
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